An integral part of all good warm-ups is stretching.
This may be the most important part of your warm-up.
Stretching increases your mobility and your range of motion thus decreasing the risk of injury and improving circulation.
With this improved circulation, your muscles are getting more nutrients flowing into them while more waste products are being faster removed.
Some byproducts of this stretching is the slowing of the aging process, the reduction of pain, and the rebalancing of your muscles.
That's pretty awesome.
Now get up and do 50 jumping jacks.
Get that blood flowing to your extremities.