Exercise is always a good thing. The level of exercise you undertake depends upon your lesions, where they are located and how aggravated they become when you do work out. Walking is always good, provided it is not painful for you to walk. There are some stretching exercises that are helpful and low-key. If it doesn't aggravate your HS, do a full body workout, by all means. There are numerous exercises on the Internet, so find some that are comfortable for you. Always remember to shower afterward as any type of exercise will produce sweat (even if you don't see or feel it) and sweating does aggravate the HS.