Cycling doesn't have to be tough. But then, tough is what you make it. I say to my co-workers that I do a few rides on a 40 mile round trip route a few days a week. They look at me like: you do that in a day .. after work?

Others I ride with say: you aren't even breathing hard as we go up some climbs .. What's tough for one is peanuts for others. But on shear heart rate numbers or calories expended per hour, cycling may be up there. Toughest? I dunno ..

But since I'm on BF, I say hail jeah!