Tip of the Week: Know thyself.

As someone who has been publishing fitness magazines for seven decades, I have doled out advice to literally millions of people, hopefully helping more than a few during that time. Still, for the wide range of instruction I've offered regarding sets, reps, calories and cardio, there is one piece of advice that I can say with absolute assurance is universal. It applies as much to the 16-year-old boy who is trying to gain muscle as it does to the 66-year-old woman attempting to get back in shape after a decade of inactivity: Work within your own specific set of tolerances.

Despite the fact that my magazines would often be full of the workouts of professional bodybuilders and seasoned athletes, we always made sure the take-home message for the reader was to use their workouts as templates, not gospel. That 16-year-old can't be expected to lift the kind of weight Arnold Schwarzenegger would any more than the 66-year-old could follow the daily cardio regimen of an elite runner.

Even when I give advice in this column, unless it's a specific workout designed for someone who writes me, you should take it under advisement, figuring how it might fit your own needs. This is why it's so important that you learn to listen to your body as you travel the road to your fitness goals. The more you know yourself, the more you can tailor a regimen that suits you to a "T."

Q: I was reading that Jack LaLanne just turned 95, and I know that you are in your 80s. It seems to me that it's no coincidence that both of you are lifetime advocates of being healthy and fit and that you're both going strong at an age when most people are just happy to be alive. Do you think genetics plays a role in your longevity, or do you attribute it to exercising?

Joe: I'm very happy for my friend Jack, who did indeed just turn 95. He's a truly amazing man, with such energy that sometimes even I don't know where he gets it from! As for myself, I will be turning 89 this November, and I have to say, despite some frustrations associated with back surgery I had a few years ago, I'm feeling pretty good. I still go to the gym every day, as does Jack.

Of course, our gyms are in our homes, which makes it a bit easier — but while the commute is a breeze, our workouts aren't. I still put forth as much energy during my workouts today as I did 50 years ago.

As to why Jack and I have lived as long as we have, I can only speculate. I do believe that heredity plays a major role in how long a person lives. Both Jack and I probably have good genes for longevity. Yet there is also something to be said for maximizing that genetic advantage. By eating healthy and exercising regularly, plus avoiding carcinogens like cigarettes, we have allowed our bodies to approach their natural potential. Feel free to follow our lead and see how many good years you have in you.

Q: I'm a 28-year-old woman who would like to build up my backside muscles. What specific exercises can I do to target the rear?

Joe: While there is just one exercise I can think of that solely isolates the gluteal muscles, several hit them nicely, while also working the thighs. That one exercise is something called the butt lift, which is done by lying on your back on the floor with your feet elevated, either on a bench or ball. You then lift your butt off the floor, tensing it the whole way, then lowering it back down.

Other exercises that target the glutes include below-parallel squats, leg presses with the feet placed high on the foot platform, walking uphill or up stairs, and using something called a glute-ham bench, which not every gym has, but is an excellent exercise nonetheless. I hope you find success with my suggestions!

Joe Weider is acclaimed as "the father of modern bodybuilding" and the founder of the world's leading fitness magazines, including Shape, Muscle and Fitness, Men's Fitness, Fit Pregnancy, Hers, Golf for Seniors and others published worldwide in over 20 languages.To find out more about Joe Weider, write to him and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate web page at www.creators.com.