Exercising Toddlers

The crib is now officially the gym!  Jude has discovered a much better use for his mattress, other than sleeping or napping on it...he's talking, calisthenics.  That's right!  He can jump, swing, bend, twist and kick, all for the low price of zero dollars a month.  Where can you get a cheaper workout than that?  He'll even drop onto the mattress when tired for a bit of a cool down, with some stretching, and of course, lots of belly laughs.  He's having such a blast, I'm tempted to try it on my own bed, but I think I'd need the bars to get as much lift as he does.  Some kids just have all the fun!  
Best,
Bubbie and Jude
P.S. How have your grandbabies taken to the crib?
Related Article:
How Much Exercise Do Toddlers Need?