Some good action poses and I like your faces with the sketchy lines. One big area of improvement would be to give more form to the shapes making up the body. You have a start in the head - next step would be to make the head seem solid instead of being flat (this does take a lot of time, practice, and understanding why it works the way it does, so no immediate hurry). As for not making it a career, that's fine. I'm just a hobby artist now, but I'm still working on self-improvement. It's fun just being able to draw.