How do you spell motivated? B-R-I-T-N-E-Y! After a 12-hour day taping her cameo for “How I Met Your Mother” yesterday, Britney headed to the Ritz-Carlton, Marina del Rey gym to get her fitness on by working up a sweat on the treadmill with her personal trainer. No naked-in-a-towel-show this time around though. Rock on, Brit. April 30, 2008.