Go talk to your doctor. You probably want some kind of steroid inhaler and albuterol. Also try to understand what your asthma is and why you have it. If there is an allergy trigger, taking a benedryl (sp?) before bed can work wonders.

I also would recommend getting a heart rate monitor. Learn what it means to be warmed up and pay attention to how your lungs feel/respond and different heart rates. For example, "warmed up" for means a heart rate of 160. I need to ride slowly until I get to 140 and pick up just a little until I get to 160. If I start out slowly sometimes I'm fine even without albuterol. If I start out quickly, I get swelling in my lungs and it can take hours to recover.