Body benefits: Cardiovascular fitness, plus toning for your buttocks, thighs, and calves.
What you need: Good walking shoes.
Bare-minimum (10 minutes): Complete the 3-minute warm-up and 7 one-minute intervals.
Even better: You may find that once you get moving, 10 minutes goes by quickly. In that case, go for 20 or 30. One idea: Walk 10 or 15 minutes in one direction away from home -- you'll have to walk the same distance back.
For 3 minutes, walk at a comfortable pace to warm up. On a difficulty scale of 1 to 10, this should be about a 3.
For 1 minute, step it up until you're no longer just strolling. Level of difficulty should be a 6 or a 7.
For 1 more minute, return to level 3 for a moment to recover. Alternate between difficulty levels for 5 more 1-minute intervals.