Running

I only worry that I am excercising too much. I climb and canoe once a week, run every other day and cycle a 12 mile round trip to work 5 days a week.

You'll feel it when you are, I did.

Last year I went a bit over the top. I was commuting everyday 6 miles each way on my bike, weights every other day, 3 mile run in the evening on non-weights days, then staying up late studying or if I was studying, out drinking.

I was just knackered all the time; falling asleep in lectures, couldn't concentrate, etc. I didn't gain any muscle mass either. I don't bother with weights now at all.