I have found a way to help my concentration and make me last for longer - it's all down to the magic of music. Blasting my iPod while skipping has really increased my stamina!!
I've found that trance club dance music and ska are fantastic, with a really lively beat and rhythm to get you going. Surprisingly, I also skip well when I'm listening to lively world music!
There are of course the obvious "mountain" songs which make me really excited about the adventure ahead:
Get On Top - The Red Hot Chili Peppers
Night on the Bare Mountain - Mussorgsky
Stairway to Heaven - Led Zeppelin
Climb Every Mountain - Sound of Music
Reach (for the stars) - S Club