Plagued by Exercise Injuries

I have been trying really hard lately to exercise, but I have been plagued by a few injuries that keep from it. I had knee problems for about three weeks which made it to where I couldn't run like I wanted to. Then last night as I was running, my stomach started hurting. I think I pulled something in my stomach somehow. So even as I sit here typing, it is hurting now. It is very frustrating to have to wait out the injuries until they get better to exercise. I want to exercise whenever I want...not have to wait awhile for my body to heal. Hopefully after this little setback, I'll be alright for awhile.