We all know our chronological age. That's as simple as counting the candles on your birthday cake. But do you know your biological age?

This second number measures not how many years you've seen, but how much those years have impacted the functioning of your body and brain. Scientists calculate it a number of ways, but whatever methodology they employ, they agree chronological and biological age don't always line up.

Some 80-year-olds function like people decades younger. They ace their memory and cognitive tests, and scientists peering at their cells can even spot significant differences. Experts have dubbed these role models of healthy aging "superagers." Just about all of us would love to one day become one.

How do you achieve that? A long and fascinating article in the latest issue of UCSF Magazine delves into the work of the University of California, San Francisco's Memory and Aging Center to answer this question (hat tip to PsyBlog). Much of this research is still far too new to be of everyday use, but science has already determined a few simple interventions you can start using today to help keep your brain young.

1. Think positively about aging.

If you try to think of famous superagers, one name will almost certainly pop to mind--whip-smart, 85-year-old Supreme Court justice Ruth Bader Ginsburg. How does she keep her brain working at such an incredible level? Part of the answer, experts say, is that she expects it to keep working well. Optimistic expectations about aging actually help us age happily and healthily.

"There are some suggestions that people who are more optimistic age better than people who aren't," Joel Kramer, director of neuropsychology at the UCSF Memory and Aging Center, notes. Just believing that old age need not be a drag helps you ensure your brain will function at its best in your golden years.

2. Practice gratitude.

It's great to know that optimism is essential for becoming a superager, but how do you become more optimistic if you weren't born with a naturally sunny disposition? Science has a simple answer to this question: gratitude.

Neuroscience shows that when you consciously choose to see and give thanks for the positive in your life, it changes the wiring in your brain, making it easier to see the good in the world going forward. And the more optimistic you are, the slower your brain is likely to age, the latest science suggests.

3. Hang out with friends more.

We usually think of hanging out with friends as a pleasure, but to your body, this activity is more than just a pastime. It's a powerful stress-busting medicine. Studies show that spending time with loved ones measurably reduces the effects of stress on your body, while loneliness can do as much damage as 15 cigarettes a day.

And stress, it turns out, plays a critical role in aging. "The greater the feelings of chronic stress, the greater the signs of aging in cells," explains UCSF psychologist Elissa Epel. That means that if you can tamp down stress, you slow down aging. Staying socially connected is one of the most powerful ways to do that. Handily, it's also super fun.

4. Meditate.

Optimism, gratitude, and staying socially connected are all proven ways to reduce stress and the damage it does to us. So is meditation. One study even showed that the brains of regular meditators appear seven years younger than their actual age. You only need minutes a day to see benefits (and no particular spiritual beliefs), and there is a ton of advice and support out there to help you get started (even if you've tried before and failed).

5. Maintain the basics of a healthy lifestyle.

And yes, finally, there is all the obvious stuff. If you spend your days on the couch munching Cheetos, your mind as well as your body is going to decline quicker than it would otherwise. So, while all the above will give you a better chance of becoming a superager, that's only true if you give yourself a fighting chance by sticking with the basics of a healthy lifestyle like eating a well-rounded diet and regular exercise. Sorry, there are no shortcuts around these essentials.

Correction: An earlier version of this column misstated the first name and title of the  researcher quoted under the header "Think positively about aging."