When it comes to sticking with our diet and fitness goals, we make excuses for many reasons, but mostly because we're not fully committed to what we want to change, so it's easy for outside influences to distract us from our intended goals. In order to help you to stay on course, I've outlined a few of the more common excuses — and ways to "excuse bust."

EXCUSE: "I'll do it tomorrow ..."

EXCUSE BUSTER: Start right now. Your diet and fitness program needs to be something you can live with forever, not something you put off because it doesn't happen to be convenient for you. You need to come up with ways to make your diet and fitness convenient and automatic.

EXCUSE: "I'm too old."

EXCUSE BUSTER: You're never too old to start exercising. The research is clear: Exercise will help you live longer, with significantly increased mobility and independence. It has also been shown to improve cognitive function and prevent diabetes — even in old age. Overall, exercise will help to improve your quality of life. Try looking for programs that are specifically for your age group. Also, if you can afford it, hire an certified trainer who has experience with older clientele.

EXCUSE: "It's useless — my genetics are working against me."

EXCUSE BUSTER: You can lose weight. It's very rare that a person can't lose weight and get in reasonable shape for his or her body type.

EXCUSE: "Cook dinner? Please! Do you have kids?"

EXCUSE BUSTER: Even if you have no time to buy healthy food and cook at home, you can still make convenience and fast foods work for you. For instance, get menus in advance and figure out what healthy offerings you might enjoy at your favorite restaurant. Or go to the supermarket and buy some tasty, low-calorie frozen dinners; some of them are delicious. You can also try batch cooking: Pick one day of the week to prepare an entire week's worth of healthy meals.

EXCUSE: "I only live once — so I might as well enjoy myself just this once. It's not such a big deal."

EXCUSE BUSTER: Really? The truth is those "one-time" events add up. I once took the time to add up my own "special occasions," and they came out to more than 60 per year. That's a lot of "one times." If you look at it in terms of calories, if those one times cost me 500 calories each, multiplied by 60 that's 30,000 calories, or about 8.5 pounds per year. Also, keep in mind, the most important reason to eat right and move more is to improve your quality of life. The more you do for your body, the more your body can do for you.

EXCUSE: "I'm too tired."

EXCUSE BUSTER: If you're like most people, you're not getting enough sleep. Research shows that lack of sleep can cause weight gain by increasing appetite. And also, when you're tired, you're less likely to be able to make the healthiest food choices. Set up your environment for sleep success. Go to bed earlier and aim for seven or eight hours of sleep. Make sure the temperature is correct and that you have the proper bedding. Get a good, high-quality mattress. Have a regular bedtime. Get rid of the TV in the bedroom and make your sleep environment quiet, both aesthetically and in terms of actual noise.

Charles Stuart Platkin is a nutrition and public-health advocate, and founder of www.DietDetective.com.