Working out and feeling good

I sometimes find that working out can lift my spirits on a bad day. Working out releases certain chemicals in the brain that help one to lift their spirits. I used to work out primarily to put on muscle, now I work out to feel good. Going to the gym knowing I must do a certain number or sets and reps is not fun for me. When I go to the gym now, I just want to get a good burn and make sure I feel, most importantly, mentally healthy. I feel my workouts are more rewarding now and I am not discouraged when I do not see results.