At age 84, Sister Madonna Buder (aka The Iron Nun), finished Ironman Canada. How'd she do it? Sister Iron says, "All I was concentrating on [was] getting the job done."

Single-mindedness is essential for endurance athletes — and also for you, as you walk 10,000 steps a day to strengthen your body and mind without the wear-n-tear of endurance sports.

Plus, mental focus lets you drive safely or read (and remember) a book on a crowded commuter train. But many folks say that over time, focus becomes difficult, and they're more easily distracted.

Researchers recently measured the brain activity of volunteers ages 18 to 88 as they watched a movie and reacted to distractions. It turns out that as you age, you notice and react to ever more diverse sensory stimuli, and that can blur your focus.

Aging, said the researchers, makes your "experience of the world ... increasingly individualistic," differing from both younger folks and your peers.

So how can you enjoy the benefits of expanding sensory awareness and hold on to the ability to focus sharply? Try these:

• Reduce mind-clouding stress with mindful meditation for five minutes every morning and evening.

• Do resistance-training exercises for 30 minutes, three days a week.

• Practice attention training: Set up tasks that require you to tune in to what you're doing and tune out distractions, such as reading while the TV is on or writing an email in a noisy room.

Now you're ready to defy expectations, just like Sister Madonna.