The “Grumpy Old Men” (played by Jack Lemmon, Walter Matthau and Burgess Meredith) made us laugh, but those ill-tempered characters weren’t doing themselves any favors. The trick to maintaining vitality for the long haul is to cultivate a good attitude and upbeat mood. We like the comedian Mrs. Hughes’ point of view: “I’ve been married so long, my oldest daughter is my age!” Boy, has she rolled back her RealAge! (Staying upbeat can make yours 5.2 years younger.)

So, if you’re lonely, frustrated or angry about the shape you’re in, listen up: Those feelings can make you grumpy and elevate your level of the stress hormone cortisol. Before you know it, you’ve got high blood pressure, heart problems, fuzzy thinking, decreased muscle tone, weakened bones and immune system and an even worse outlook on life.

Here’s how to stay on the sunny (and healthy) side of the street.

1. Move it and shake it up. Exercise keeps your brain sharp and attitude positive even more than words games or puzzles. Walking daily does the trick, indoors or out. We say aim for 10,000 steps a day.

2. Eat right. No food felons (trans fats, saturated fat, added sugars and sugar syrups, and any grain that isn’t 100 percent whole). Poor nutrition makes it tough to fight stress, feel happy or defeat disease.

3. Reach out to family and friends. Staying connected increases happiness and good health and makes you 8.5 years younger (with a calendar age of 55, that means you’re only 46.5).

The You Docs — Mehmet Oz, host of “The Dr. Oz Show” and Mike Roizen of Cleveland Clinic — are authors of “YOU: Losing Weight.” To submit questions, go to www.RealAge.com. A King Features syndicate.