Heisman Trophy winner Johnny Manziel of Texas A&M says he's learning every day about life as a celebrity.

The first freshman to win college football's top award said Thursday he was trying to avoid making ``the same mistakes again'' after a picture of him holding cash at a casino was posted to his Twitter account on Saturday, a day after the Aggies beat Oklahoma in the Cotton Bowl. The picture was later removed.

The celebrity website TMZ published pictures of him holding a champagne bottle at a Dallas nightclub the same night.

Manziel was on a conference call to accept the Manning Award given to a top quarterback after bowl season.