You haven't met me, then :-D I used to be quite fit and lean and I'd stil sweat at the first sign of physical activity.

On the other hand, if we're both stuck in chilly weather with just shorts, a t-shirt and an unlimited supply of calories, you'll probably be the first one to freeze to death :-p

No doubt that is true, but to encourage people to cycle to work it's probably necessary to have a shower in the office - just to eliminate that as a source of anxiety.