Money's worth in sweat and pain

Found a free afternoon to run solo at the fitness club. It's almost like my second home already. Campus is still first. Why have I been spending so much time at a place of torture? One, I spent a lot on it already so I feel like I have to milk my money's worth in sweat and pain. Two, I'm scared. A few breathless nights weeks ago reminded me how much I enjoyed breathing. It's an activity I would like to be able to continue doing for a while more yet. If building up my cardio-vascular endurance is going to help (as per doctor's advice), then I'm all for it. Mmmm... breathing.