If you have 10 minutes to spare try this circuit:
This can be done with running, running in the spot, biking, elliptical, or a treadmill
#1 Sprint 10s - Rest 10s x 3
#2 Push ups 20s Rest 10s x 3
#3 Mountain climbers 20s - Rest 10s x 3
#4 Burpees 20s - Rest 10s x 3
For Burpee explaination see: http://aliciabellelite.blogspot.com/2011/07/burpee.html
At the end you should be feeling like this!
Good luck and let me know how it goes!