I want to become athletic

[Cavernio]

Ok, goal is to become more athletic. Why? Because I think this will be fun. This is important to me that whatever I'm doing I'm feeling good about it, not because I'm avoiding a bad. So yeah, I think it will be fun.
So, the mental side of it is more or less taken care of as long as I am looking at this as fun.

The next side of this is starting and doing this safely without hurting myself, but also without being too cautious.

So my physical health really isn't great right now. I'm 195lbs last I checked, 5"1', don't purposefully exercise but do walk everywhere for like, groceries and shopping and stuff, which isn't a whole lot of walking.
I'm also smoking weed regularly. I would absolutely have to nearly cut that off completely, stuff makes me sluggish. Plus lungs etc.

Biggest thing is that I'm living in near constant physical pain lately. Nerve pain mainly, it moves around, throbbing. But I realize that I think I ignore a lot of pain signals, naturally just do at this point, so it can become hard to tell when I've pushed myself too much or not. eg: Last time I moved I pushed myself too hard to the point of like, not being able to get myself out of bed for a week, the exertion and stress just shut me down physically and mentally.

Does anyone have any advice or know a good place to look for starting an active lifestyle while dealing with chronic pain?