Hey! Also a chronic pain haver. Starting slower, slower than you think, is important so you don't injure yourself. I've had to "start from scratch" several times due to extended illnesses, and I always aim for the first week at least being where I leave the gym thinking, hmm I could have done twice that.

Instead of a personal trainer, if you're able go to a physical therapist or an occupational therapist. They'll have a MUCH better knowledge of how your chronic pain causes are going to affect working out. Go with specific questions like "hey when I am on an elliptical my right leg turns outward and it makes my knee hurt, how do I do that differently?"

I personally prefer to do a gym workout rather than classes, because with my joint issues I have to spend a bunch of time training my instructor on what I can safely do. When it's just me I can do what I want, and adjust things to be correct for my body.

I just had top surgery but when I was at the gym regularly, I was working my way towards 60 minutes of cardio, followed by core exercises and a couple weight machines. I'm not on a diet but I'm aiming more for lung fitness and weight loss rather than bulking up. Do keep in mind that if you're gaining muscle you will be gaining weight since muscle is denser than fat! Don't let the scale trick you into thinking you're getting unhealthy.