Exercising is a must do for me, even with the pain of HS. You are having challenges with walking so it's really hard to gauge what you can do physically. You probably know what you can handle and what you cant. I personally can still walk, run, swim and play soccer but find that the stair climber is so much harder now because of sores in my private areas.
It's good to exercise and if your like me you'll feel great afterwards. Some people have mentioned on this group how sweat makes their HS worse and I've notice that if I don't shower right after I'm done working out my HS gets aggravate.
Find something small that works for you even if it's simply walking around the corner or swimming.
The best advice I can give you is to make sure your 110% comfortable in what your wearing before you do anything, that might be obvious but I learned the hard way.

xoEsmee

Low Impact, low sweat activities are good.

Swimming, Tai Chi, or Yoga (Ashtanga, not Bikram!)

I tend to do more weight training that cardio at the gym. So I am not causing too much friction where my HS is situated, I don't see too much flaring up afetrwards.

Because my sores are in the lower part of my body, I find anything like walking, running, treadmills or using the elliptical are a big no. It will just cause more pain for me in the long run. So instead of doing that kind of exercise, I lift weights! And even do it in the comfort of my own home :)
I can do a full body workout, within range of what I know I can do, and not get any flare ups. Hope any of this helps!

I'd like to do yoga again but having sores in my armpit means basically anything that involves raising my hand higher than shoulder-height is not a good idea right now. Weight lifting did occur to me but I don't have the money to buy weights or get a gym membership. :/

It's annoying because all of the kinds of exercise I actually like are just not currently feasible.

I have both armpit and groin areas that hurt if I move in certain ways, like walking for more than a few blocks. It may sound silly but I crank up the music and dance around my apartment. Not really a focused workout but for at least some cardio and I can move in a way that is comfortable for me.

WHATEVER works for you! Some days all I can do for any sort of activity or exercise is clean the house or even just going to the store to walk around. I do the same as KC3478 and crank music up and dance around :P ANYTHING to get your heat beat up is a good thing :)

As a side note! I got 2 5lb weights from the second hand store (pretty much in new condition) for $5 total. :) I know money is tight in my household and second hand stores are always a good option!

I agree. try Yoga. I was actually thinking of doing that as well. Swimming sound nice too

Well, like I said, many yoga poses are off limits because they involve more shoulder movement than I'm willing to do right now. I know there are modified forms of poses for people with knee/back/hip problems but I don't know of any for people with issues around the shoulder...

I'll guess I'll just have to start walking whenever my thigh/groin sores get better.