I think it's one of the reasons it's quick at the beginning! Otherwise, it would be a lot harder to keep at it!
Its officially too hot to do anything at the moment incl exercise. Its 7.15pm and 80 degrees farenheigt with like 1000% humidity so all I'm doing is keeping up the water intake. Its meant to be like that for the next week so will have to do some mall walking I think in airconditioning.