Always had lucid dreams....now want to use them.

My lucid experiences started at age 9-10. It all started when for a few days I had a paralyzed feeling when I woke up. I as extremely scared and did not know what to tell or if anyone would believe me so I kept quiet. Eventually this graduated to 'lucid dreaming' and then complete dream control. However this ability is inconsistent, sometimes I can do it for the whole night. other times only for only a short time. It seems like a constant fight not to wake up. Now that I am 21 I want to learn to take advantage of this ability to improve my normal life abilities(sports, academics, etc.) As I try to increase my control over the dream, I seem to start losing control over my "state" and wake up. Does anyone know of techniques to strengthen the lucid state so that one can stay through mentally intensive tasks such as problem solving or playing sports?