Children are naturally flexible. And they have boundless energy. I know this, because I have three sons:
5 - 3 - 1 year old.
Did you ever try to keep up with children?
In fact, when PROFESSIONAL athletes have tried to keep up with a child, they get exhausted within an hour.
Before my son hit the crawl stage, he had to do baby pushups - not to mention a lot of back hyperextensions.
In order to achieve the sit-up-in-bed stage, he had to do a lot of leg lifts and knee pullins. One of his favorite exercises was the "army crawl". That one whoops most adults within a few seconds.
After army crawls come "bear crawls".
Bear crawls are one of the most overlooked bodyweight exercises - and if you take a minute a day - well, maybe more like 30 seconds to crawl like a bear - believe you me, results are a coming down the pike.
After bear crawls flip over for a bit of crab walking, and you've virtually hit every muscle in the body, except the neck.
Now: how could this be turned into an Exercise workout?
1. Baby pushups - hips and legs on floor - push off palms, lower
2. Army crawls - 10-20 seconds
3. Leg lifts - 10-20 to start
4. Leg pull-ins - 10-20
5. Bear crawls - 30 seconds
6. Crab walks - 10-20 seconds
7. Get-ups - lie on back and come to standing - 10x
So you see, even the most basic things we do as a child can be turned into a kick-butt workout, using nothing more than your own bodyweight :-)