We Run This...Missy Elliot (from Stick It)
Get Up...Super Chick (I love it...it's about no tbeing afraid to fall)
Up Up Up...Rose Falcon (Watch out world!)
Hero in You...KSM (team USA's theme song in Beijing)
Let it Rock...Kevin Rudolf (not really gym, but I love it because it's fun and gets me excited)
The Climb...Miley Cyrus (we made our track video to this-well part of it-and it was great)
Go Figure...Everlife (about not being upset when things don't always go right, keep going)
Here it Goes Again...Ok Go (let's go!)
How Far We've Come...Matchbox 20 (self explanatory)
I Hope You Dance...Lee Ann Womack (awesome if you're doing it for a child/niece/nephew/grandchild, etc)
If You're Gonna..Natasha Bedingfield (about going all out)
Move Along...All American Rejects (move along, move along)
No One...Aly&AJ (it was in Ice Princess...yeah)
Stronger...Kanye West (I think most sports people know this one by now)
That's What You Get...Paramoure( That's what you get when you let your heart win)
Unwritten...Natasha Bedingfield (release your inhibitions!)
How Strong Do You Think I Am?...Alexz Johnson (actaully about a relationship, but hey)
Ok so these would be good for different reasons, depending on what kind of video/what you're going for.