When I sit down to play my cello, I find it very relaxing. For me, the cello is easier to finger than the viola or violin. It seems that, for me, I don't have to bend joints in ways they are not meant to be bent. It seems like it is more natural to sit with a cello, finger the fingerboard and bow. I notice this every time I sit to play one of my instruments.

It is not that I find it easy to play the cello. I will be a student of cello forever. I think it is just easier for me to do the arm and finger movements needed on cello than the viola/violin. 

I find it relaxing. I grab my cello and bow, sit down, pull the endpin out where it needs to be and give my cello a little hug. I never give my viola or violin a little hug before playing them. I just do it to my cello. I have no idea why that is. Maybe, with the cello leaning against you, you become one and you just give it that gentle hug before starting. Maybe it is an, "Okay, here we go," or "Okay, you can do it," sort of thing, simply because of the position of the cello and it's size. It is not sitting precariously on my shoulder. It is solid on the floor and leaning against me as if we are one. 

I must be somewhat of a person looking to be a glutton for trouble though, because even though I find my cello to be relaxing, I do enjoy my viola and violin.

At any rate, I do find the cello to be very relaxing, in many ways.