I do Circuit Training once a week

I'm just under 13 stone and 6 foot, age 26

i can do 40 from cold with no breaks......but during an hours class probably do a hundred or so with the same amount of situps, crunches, squats blah blah blah

I was crap when I started tho! Took about 4 weeks to get into it and keep up with the rest.....just old injuries that stop me doing it more often