Absolutely. 

Some days, not just violin, but music in general.  Too old, not enough talent, didn't get/make the breaks, too stupid too.. well, the list can go on and on, but yup.  Probably not all that different.

Such times happen, Coolpink.  I know I get them.  And I have known some excellent musicians over the years, a few of them ones most people might consider "successful", who still have days like that.  So, logically, it isn't actually due to lack of ability or anything like that.

Knowing such days come along is why I set up my practice routine the way I did.  It's all fundamentals, and it starts with stuff I know I can't mess up and doesn't go any further than stuff that is currently pretty easy to do fairly well.  It is a realistic amount of time and broken down into pieces/sections so no matter how many interruptions, I can probably still get through it.  Then, after I get through it, then I play!

I've sabotaged myself enough times over the years to know how I do it, and to make plans to try to avoid it.  Keeping what I actually practice "idiot simple" may not be much ego gratification, but it works for "default" or "minimum" setting.  I also know from past experience that it is not really possible to practise too much of the basics, and that every improvement on the basics improves all the rest of my playing. 

I have a view on practise/play that some people maybe find a bit odd.  Practice is work and exercises I do so that when I go to play, I can play better.  I don't see them as the same thing.  One thing I figured out years ago, is that all the practice in the world won't make someone into a good player.  If you want to play good, you have to play.  And just like anything else, at first it will not likely always go great.  LOL

But I have known people who put in insane amounts of practice and study, and never made it out of their own bedroom with music.  They were "serious".  Some of them "started young" enough, some had great gear.  And still, they didn't take the step, they just expected practice to somehow turn into good playing.  Sadly, for some of them, it never really did.  Practice is like education in a way.  It is preparation for an activity, but not the activity itself.  Somebody can go through college and get a degree in whatever and still not do well in the workplace or even get a job in their field.  To repeat, practice, like education is preparation for an activity.  A necessary step and continuing need, but not something that just automatically turns into the activity itself.

Now when you have gotten together with your jam partner, then you are mostly playing.  Sure, you may learn a lot, but the exercises and thinking and effort you put into your practice sessions can start to pay off a little then.  Instead of just "paying dues", you get to collect on those dues a bit. 

So anyway, my advice on practice is to keep it basic and keep it what you are sure you can do so far as time and goals.  "Shoot the fish in the barrel."  And then you'll be warmed up and have some skills that gradually build that you can see what you can do with when you pick up the violin to "just" play songs and make some fun music.  But only "officially" practice for a short enough time that you know you will be likely to do it, and practice basics like open string bowing, string changes, metronome work against the simplest and most basic beats, intonation.. Things where even getting a tiny bit better can make everything you do better when you pick up the violin to actually play songs or play with or for someone or do a recording.  After that is taken care of, "chores" are over and then you try any song you feel like, and just play for the fun and joy of it.  See what you can do. 

Back to the original point though, that is how I get through it.  On bad days, I "shoot fish in a barrel".  On good days I can manage some better.  And each day has its little bit of progress and experience, and those will add up over time.

So far as the thoughts of it being a waste of time and money.. Well, I can sure think of things that will kill you quicker and get you into more trouble than music and a few instruments.  Music is a sensible choice, comparatively.   LOL

@StoneDog: Shedding..  I *like* that symbology!   Good one, StoneDog!

@coolpinkone:  And you'd think, that after as many years as I've put in and the assorted instruments, I'd at least have "how to learn" figured out better by now.. But nope!  LOL

The first several months of my first year on violin were spent trying to learn a bunch of songs and rushing into practising "more advanced" scales instead of basics.  There's actually nothing wrong with those things, but you can get more out of them with some basics. LOL

I lucked out and got reminded to take it back to basics.  Several months into the first year, right after I got my Hoffmann, somebody told me that for the first few weeks I should go off in a woods or lock myself in a closet or whatever, but play just open strings on it as LOUD as I could for a few minutes avery day for the first couple of weeks.  That it would help the instrument settle in and begin to develop it's "forte voice".  Some guitarists (myself included) feel that is a good thing to do with new guitars, so it made sense, and I was doing that.  

Then I was talking with another acquaintance (who knows considerably more about playing violin/fiddle than I do) and I was griping about my sound/playing.  They asked me to explain what I felt the problem was, much like we all do with anybody new who wanders into the chat and is complaining about sounding like Skrat scud.  I had to think about it for a couple days and then told them that, as I would say it in guitar terms, it lacked "authority".  Not an official term, but just what I've always used for how a beginner sounds different than someone who has been playing a while.  There is a certain hesitancy or weakness to their sound.  They sound more like they are trying to not mess up than really trying to say something with the instrument.  So I got told that the issue was probably "tone", maybe some articulation.  And to just focus on those for a while when doing my open bowing.   

I had been finding open bowing to be pretty dull and was kind of glad to think I was almost done with it.  So that wasn't really what I wanted to hear.  So I did what any musician does when a more experienced player tells them what they need.  I argued and complained, like an idiot.  LOL

They kept focusing on how easy open bowing is, since you don't have to worry about the left hand fingers or intonation and the left hand can practise "staying loose".  I argued that is is boring, even for 15 min.  "Break it down into three sessions of 5 minutes then, if that's more comfortable at first."  I said that it was a the boredom that would be the problem, not it being too complex.  Wouldn't maybe some etude or exercise that had some fingering involved be better?   It's 4 frackin' notes.  A baby could play 4 notes.   "Perhaps.  But could a baby make them sound good?" 

Uhh.. umm.. ok.  I finally got the point.  I'd been working on learning more songs and more "advanced" scales, but not really working on making them sound good as the priority.  If  somebody pro played that one open string note, even on my violin and bow, they'd make it sound like singing.. "LAAAAAAAAAAAaaa", whereas I was sounding a bit more like the bleat of a rather anaemic and not overly enthusiastic sheep.. "baaaahhh."  But something as simple as bowing on an open string, I should be able to sound as good at that at least.  Right?  Well, no.  LOL  But now I had a problem/challenge where I had a way to work on it and where I could hear the difference.  So I did the exercises for a week.  There was maybe a little difference.  Another week and I could definitely hear a difference and see where it was kicking up my sound up a notch when playing.  After I was sure of that, well, then open bowing exercises became a daily necessity instead of a bother. LOL

I've probably gone too far into this, but I think it is a good example.  Like when I was saying that practice alone will not make you a better player.. Neither will exercises alone.  The exercises are tools you can use to work on different parts of your playing.  Once you realize that, and start to hear them make a difference when you go to play a song later, then they stop being boring.   You might start with open string bowing and for the first 5 minutes, you try to make the notes sound very smooth and steady.. The next 5, you might work on making them very strong/powerful/loud.  Then the last 5, you might just try to incorporate the things you figured out in the first two sessions and just try to see how good you can make it sound.  Other times you might focus on your bow hold or using your elbow and wrist better or whatever.  That's the sort of thing that makes it get better, not just "doing repetitions". 

And anything basic like that will help with everything you play when you just go to pick up the violin at any time and have some fun playing. 

UtahRoadbase said
Also, I have had tearful days since I started and probably won't ever stop having them. When I was a child, I argued with my mother to let me quit and now, as an adult, I beg MYSELF to quit.

I hear that, URB.  Like I tell people.. "I've given up on music a few times over the years.  It has never stuck though, because music doesn't seem to have given up on me, yet. "