"Fat March" (ABC)

Contestants will follow a simple workout regimen: walking, walking, and more walking. It's an ingenious idea to remind viewers that workouts don't have to be complex or expensive. The participants don sneakers and walk from Boston to Washington, D.C., crossing through nine states in the process.

Highlight: The stunned looks on the contestants' faces in the first episode, when they are first told they aren't living in a luxury manse for their weight loss, but will be, yes, walking and camping.

Incentives: Shares of a mega-prize of more than $1 million, plus mini-prizes like spa treatments (and, we hope, extra moleskin for blisters) along the way; teamwork is rewarded as much as individual weight loss. Go team!

"Shaq's Big Challenge" (ABC)

Basketball star Shaquille O'Neal focuses his show on kids, to try to nip the childhood obesity problem in its oversized rear. This season features six Florida children and the programs Shaq has helped design to get them to change or adopt new eating and exercise habits. The "Challenge" here is huge, since children are dependent on their parents and schools to help reinforce the good habits, but Shaq has surrounded himself with a team of coaches, chefs, doctors and others who encourage -- and really push -- the kids.

Highlight: James' incessant burps as he outlines the source of his problems: "I think fast food is what's made us the way we are. Oops, sorry, did it again!"

Incentives: If each child loses 20 pounds, the whole gang gets to go to a Heat game (peer pressure is at work, too); they're pretty "out there" being on TV, along with their schools and parents, so they better buckle down and get the job done; and who wants to argue with a 7-foot NBA powerhouse, anyway?