It's a wonderful idea, just like any artistic undertaking.

I paint and draw sometimes or just color adult coloring books, and I can tell you that when I am fully immersed in this I am the happiest..I wish I could dedicate myself to some kind of artistic endeavor completely and lose myself in it..but, unfortunately, there are too many internal barriers a.k.a emotional blocks for me to do that..so I do it occasionally for therapeutic purposes only whenever things become too dark or too stressful..I, actually, at some point, about 20 years ago was going to become a graphic designer and completed an online course for that. I LOVED it and I was, actually, good at it. Then, some tragic event happened that got me thinking about doing something humanitarian..

I firmly believe that the main root of human unhappiness is inability to unlock one's creative potential and to let oneself create in a carefree way like a child who is just playing and doesn't think about how good the result of their play should be..That's why doing anything creative can be very healing if you really allow yourself to do that.

So, yes, go ahead and play any instrument or sing however you want. Go by instructions if you want to. Do it in whatever way you enjoy it because the most important thing is to enjoy that process, not to produce results..If you manage to get into it, you may find that you don't need therapy any more or your need for therapy could be reduced..