Possible Clues:

• REM isn't in the mainstream and that sustains you when you're playing for a long time
• Fortitude of saint, a man I flogged
• Wrong about cap on American energy
• Tim with NASA developed staying power
• Staying power in a man -- it's unusual!
• Constitutional strength
• Ironman competitor's need
• Strength enlivens revolutionary saving energy
• Energizer Bunny's asset
• Parts of plants sustained energy