The most inspirational article I read this summer was written for the LA Times by Roy M. Wallack. Wallack, who is in his 50s, did something rather noteworthy.

In one day, he lifted weights for two hours, rode a mountain bike up a hill that ascended 2,200 feet in only four miles, paddled a paddle board on the ocean for an hour, and finished it all with 11 full-hang pull-ups. The entire workout took nearly five hours.Yet Wallack's workout was not my source of inspiration. I was moved by the man who concocted this exercise insanity, but not because he was better than Wallack at all the aforementioned activities.I drew all sorts of motivation because this man, Don Wildman, the founder of the company that's become Bally's Total Fitness, is 76 years old.If doing that sort of workout at that age seems impossible to you, here's something that will be even harder to swallow: Wildman, who has completed nine Ironman triathlons as well as the ultra-endurance cycling event call the Race Across America, is actually as fast on his mountain bike now as he was back when he accomplished those feats.That's because he's increased the amount of weight lifting he does. In Wallack's article, Wildman says, "Strength helps cardio . . . . As you get older, the fall-off in strength is greater than the decline in [maximal oxygen uptake] unless you fight it."And is Wildman ever fighting to keep his fitness. Working out with a partner like Wallack, who is more than a quarter century younger, is typical. Wildman's group of workout buddies include Laird Hamilton, the former surfing pro who is now 46; Chris Chelios, an NHL star who is 47; and John McEnroe, the former tennis great who is now 50.Surrounding himself with younger guys makes competing against guys his age easier. Wildman won three gold medals and four silver medals in cycling events at last year's World Senior Games.So did I tell you about Don Wildman so that the senior citizens of Carbon County would get so motivated that they would collect dozens of medals at the next World Senior Games? Hardly.I shared this story with you because of what Tim Commerford, 41, and the bass player for the heavy metal group Rage Against the Machine said to Wallack for the interview about Wildman."I was in my late 30s and already starting to think slowing down was natural. Then we rode together . . . . I thought, 'What's my excuse? I gotta train more!'"What's your excuse? Exercise is unlike most endeavors. Moderation is not best.Provided you intelligently build up to it, what's best is more. Or harder.That's not just the opinion of some loop job who loves long and hard workouts. It's proven medical fact.In the July 2009 issue of Exercise and Sports Sciences Review, for instance, Norwegian researchers concluded that high-intensity interval training improves all aspects of heart strength and heart function. Other studies have found other benefits to interval training over moderate exercise.One found a greater increase in HDL cholesterol, the "good" type. Another determined that intense exercise was more effective in treating diabetes. A third found that the death rate from cardiovascular disease was lowered by intense exercise when compared to less-intense activities like walking, bowling, golfing, and dancing.To do this sort of training, simply do a typical run or ride, but make certain segments really fast and here's the hard part for the hardcore and certain segments really slow.Besides helping your heart, interval training also burns more fat than moderate exercise during and after exercise. While moderate exercise burns a higher percentage of fat, intervals require such higher energy expenditures that the total calories of fat burned is higher for workouts of the same length.An added bonus is that interval training causes you to burn more calories up to 24 hours after exercise, which if you eat properly means fat continues to be burned all day.Despite all these benefits, interval training is not the sort of workout you can do every day. That would lead to burnout if you're lucky and injury if you're not.Strive to do two interval sessions a week, possibly three if you're in the early stages of a sharpening phase that leads to a competition.