A 20-minute workout with no equipment

Do this 3 times a week. Rest 60 seconds between rounds.

Warm up (3 minutes): march on the spot, arm circles, a few slow squats.

Then 3 rounds of:

1. Squats: 12 to 15. Sit back like there's a chair behind you.
2. Push-ups: 8 to 12. On your knees or against a table is fine.
3. Lunges: 8 each leg.
4. Plank: 30 seconds. Straight line from head to heels.
5. Glute bridges: 15. Lie on your back, push your hips up.
6. Jumping jacks: 30 seconds.

Cool down: stretch your legs, chest and back for a few minutes.

To make it harder over time: add reps, slow down the lowering part of each move, or do a 4th round. When 15 push-ups feel easy, try them with your feet on a step.