Also, two years ago I developed a semi-serious phobia about flying. I have always been a somewhat nervous flyer but after a bad experience (emergency landing...not a horrific one, but still a scary experience) it got really bad. I had some therapy which helped and now things are better again, still not great, but better. But I am pretty sure the phobia was exacerbated by just a general buildup of stress.
I also now realise how bad it had become because now I feel so much better. Not perfect...but more balanced and healthy and happy than I have for at least three years. And I think...maybe even more than I have for something like seven years...no joke. A lot of these realizations can be in retrospect.
By the way, do you know what your e-type is? Realising that I'm almost certainly a 6, as well as knowing I'm INFJ, has helped me discern some things and patterns of behaviour.
By the way, yeah, if you feel like you should start "forcing yourself" to do things again that you really enjoy, DO IT. I try to schedule those plays, art galleries, etc etc into my life semi-regularly. Fortunately I live somewhere I have access to a lot of this. I know it's not something you can always have time for, but if it refreshes you and you enjoy it, you should do it. And yes, keeping in touch with/getting back in touch with old friends is really great.
Basically, I think that if you enjoy something and it makes you feel better, and it's not illegal or immoral (in whatever way) you should do it as often as you can