@dKnockKnock -

Welcome to the Fiddlerman Forum!  

I'm sorry to hear you struggle with depression - it's something I've been familiar with my whole life (and still struggle to keep at bay), plus debilitating pain on top of it for the last 15 years. 

I believe you can make sure you end your practice in a positive way if you give yourself permission to step back when you are getting nowhere good.  It's important to challenge yourself, but you can always take time to slow down what you are working on & focus on a small section, or switch to something simple you love & know better, just to end well. 

Taking a break just listening to a piece looped, concentrating on tough parts, can help your mind & body prepare to work, better.  You can always have another go at what was giving you trouble, later, or the next day. 

Look for the smallest good thing - they are all victories and worth more than anything negative.  

It would be helpful to know approximately how long you've been playing & if you are self-taught or have a teacher?  There are some great threads here about good ways to practice - here's one:  3 Essential Ingredients of an Effective Practice Session Thread

I have to keep stress to a minimum, and I try to keep expectations realistic, especially of time/progress, because it can be self-defeating.  My focus is on playing what I know, better - and I like to to explore new music ideas & techniques, just to see where it goes, with no time limit. 

Thinking positive, like the violin, is something learned and the more it is practiced, the easier it gets. I started by turning it into a game (how many positives can I find for everything negative) - 'the glass really is half full' & over time it's become a habit.  Surrounding yourself with people who think positively and are supportive (like here on the forum) can be VERY helpful.  

Sometimes even new strings, new rosin or new bow hair can seem like sunshine on my practicing!

- Emily