Ha! That is interesting. At the beginning of my time in the gym is usually the only point at which I successfully make it up something. I mean, I start with something easy, to build confidence, but even so; after an hour or so, I won't be able to make it up the course I went up the first time. The more tired I get, the more grumpy and cautious my body gets, until I find myself getting adrenaline responses to very minor slips.