Because the mantra used to be that 20 minutes in cardio is what you needed - so 5 minutes of warm up, 5 minutes of cool down and 20 minutes of workout was the formula based on the 'research" for how long you needed to exercise to burn fat. Because, of course NO WAY would anyone want to actually work longer and harder if they only needed to do 20 minutes...
Restart 5/18/15 began at 263.9. All time high was 275 in 7/03. Low in Summer 2012 of 169.
A for every 5 pounds lost on the weight loss reboot: