If you've passed the half-century mark, it's likely that your body isn't bouncing back like it once did. Your lower back might be feeling the pain of yesterday's raking session, your left foot might still ache from rolling it while trail-running back in July, and then there's the knot behind your right knee from a skateboard incident more than a month ago.

But you can't give up, especially if you want to do the things you love — bicycling, hiking, running, golf — well into your 60s, 70s and 80s. Here are some ways to stay in the game:

As we age, warming up becomes more important, according to Laura Cisneros, founder of Urban Animals boot camp in Austin, Texas.

"Tissue gets less elastic as we age," she said. "We warm up with the idea of gaining maximum flexibility. Once the muscles are heated up and more pliable, you want to increase that range of motion, which is another thing we lose as we get older."

She incorporates medicine ball work into many of her workouts, because they allow you to train at maximum range of motion with velocity and increased flexibility. Then, it's on to strength work, which helps boost creation of energy-producing mitochondria in our cells.

"That's the nirvana for fighting off aging, from the muscle and movement perspective," she said.

Cisneros recommends spending about 40 percent of each workout on flexibility and mobility, then splitting the rest of the time between cardio work and strength training.

Jim Owen, author of "Just Move! A New Approach to Fitness After 50" ($22.99, National Geographic) has a simple message: Quit sitting so much.

"It doesn't really matter what you do," he said. "My motto is simple — start from where you are, forget limitations and do your best. And remember, your favorite chair is not your friend."

At 76, Owen spends an hour stretching and exercising, five days a week.

He begins each exercise session by throwing a couple of air punches, something that usually raises a few eyebrows. "People ask me what the heck I'm doing," Owen says. "I tell them I'm fighting off old age."

According to Owen, cardio work alone isn't enough. Core work, flexibility, balance and strength training are essential, too.

And no amount of exercise will make up for a poor diet.

Amy and Damien Temperley recently launched Aging Is Cool, an Austin-based wellness program for clients 60 and older.

Amy suggests light weights, balance work, stretching and dancing as well as yoga and tai chi.

"It's really all about getting up and moving — walk around the living room, walk around the dining room table. Swing your arms around," she said. "Just don't sit so much, because that's the quickest way to decline rapidly."

Oh, and work your brain.

"We include brain health in everything we do, and some of that is really about trying new things," she said. "Go a new direction to a familiar place like work or the grocery store. Try something different. Don't spend so much time in front of the TV. Interact with people."