Your kids say they're into the Challenge, but they're headed out with their friends this afternoon to the fast-food joint — now what? When they see their buddies sinking their teeth into those double-stacked greaseburgers, washed down with super-sugary sodas, and topped off with extra-large orders of fries, their willpower will surely fade.

Don't despair — be prepared! Almost anywhere your kids eat will have healthy options (or at least less-awful options that can be made healthy with a little imagination). Remind your kids that they can have a salad or try the burger with a whole-wheat bun if it's available (or toss the bun); they can order water instead of soda; and they can skip the fries. Tell them to pass on the dessert entirely (remind your kids to check in with themselves as to whether they're really hungry for it) or split a treat with someone else.

Encourage your children to tell their closest friends that they're trying to be smarter about what they eat. Older kids can be especially enthusiastic about healthy eating, and your child can start a trend. Friends can be allies in social situations that challenge willpower, giving your teens encouragement, and maybe even joining them in the effort