For me, it's the challenge of getting one more hold higher...a great life metaphor and all that. We all hit this wall "the snake" three or four times per visit to see how much further we've come since the last time. Some visits are disappointing, and then there's a life assessment. 'Did I have a hard week? Did I get enough rest? Did I eat right?' What's been great for me is that I can compete equally with my male climbing partners. I have advantages. I'm also aware that if I get higher than they do, they will hit the wall again and try harder until they pass my hold. So long as I keep improving, I've been telilng myself, I'm happy.
In the meantime, I notice that my fingers are stronger than they were last October. My hand can grab a round hold (no lip) and squeeze without slipping, and I've used only my thumb a couple of times now.
My legs are stretchier, more dependable. I suddenly get why Yoga would be so useful in terms of having more mobility -- Anything I can think of to make the body healthier and stronger, I'm all for it just so I can reach that damn higher hold the next time!
But the best part is that my children watch me doing this, cheer me on, and there's no tv or computer screen anywhere in sight.