I’ve got no numbers to back me up, but the P90X program seems to be working for me: 

I had planned to do a 1:00-1:15 treadmill run today.  Instead, I spent 2.25 hours  clearing my driveway of ice. 

The driveway is 85′ by 12-18′ and I had to use 6″ wide flat cutting shovel to break the ice, and then a standard snow shovel to clear the debris. 

I approached the chore as a set of intervals:  Break up the ice through a section, (high-HR, low duration) pick up the debris (lower HR, core, back & arm work, longer duration). 

Came back inside totally drenched in sweat, muscles twitching, with spasms of nausea. 

In a word, Spent. 

I still hate winter…