When do you hit the 'prime of your life'? (You might be surprised).

What the hell is ‘the prime of your life’? And how the hell do you know if you’re in it?

Do you believe it hits at a definitive age?

There’s good news: You’re probably in the prime of your life now. And there’s great news: the prime of your life comes at different times for different things. So essentially, you’re always prime for something.

A recent investigation by the BBC examined everything from fitness and memory to general life satisfaction and sex drive. We think you’ll be pleasantly surprised by the findings.

Our sex lives and overall life satisfaction.

If our lives were a movie, we wouldn't even be having sex past 30. But this is real life. And it turns out sexual activity doesn't even START to decrease until we hit our late 50s. Woo-hoo!

The BBC article and paper examining “sexually active life expectancy” reveal men who are 55 today can expect another 15 or so years of relatively frequent sex; women of that age can expect slightly more than a decade.

The study also show that although the intercourse won't be as "vigorous" as it once was, a good 30 per cent of healthy people aged 65-74 will still enjoy sex at least once a week.

And there is also a silver lining to a falling libido which hits around mid our mid-50s - an unexpected surge in our lust for life. It's a fact that might seem hard to fathom, given physical complaints rise around the same time. The boost comes down to finally learning how to balance our lives and emotions. Basically we stop sweating the small stuff and just start to enjoy our lives.

People in good health also enjoy about five more years of sexual activity at the end of the life. Some might even consider it the elixir of life.

So is there a peak time in our lives for sexual activity? It's really a quantity over quality thing and although there is no optimum time, it is heartening to know that it doesn't expire - it just becomes more considered.

Physical fitness.

The fantastic news about your fitness "prime" is this: it's ever-evolving.

In fact, as you age, you become better placed to enter "ultra endurance" activities such as marathons and triathlons. Even though your ability to perform these will start to gradually decline during your 30s and 40s, it is very steady. This week, 92-year-old Harriette Thompson ran her 16th marathon. Her story was made even more inspiring when she revealed she only took up running when she was 76.

The peak prime time for short burst activities like the 100m sprint or a spin class is your mid 20s, and while it's not impossible to continue as you get older, your ability to participate at full throttle will wane as your age increases.

In a nutshell, your physical fitness never quite reaches it's prime, it just evolves with each stage of your life. Different activities are simply better placed for you to enjoy at different points in your life.

Your mind doesn't fare quite as well...

After your 20s and into your 30s, the ability to commit new facts to memory isn't as good as it once was. But don't take it to heart - it was starting to decline right after you left school.

Our "working memory" (where you might, say, commit your grocery list to memory), steadies out for a little longer but starts to decrease slowly in our 40s.

Another fun fact: most Nobel-prize winning discovering were made around the age of 40.

But it's not all bad news, and although facts will take a little long to sink in you will develop other skills as you age. Reading comprehension and arithmetic, for instance, continue to strengthen into middle age.

Even better, our "social reasoning" - the ability to navigate and understand the complexities of relationships and friendships - becomes better adjusted and well honed. Our general knowledge also reaches its peak in our 50's, which proves even thought we *think* we know everything in our 20s, we really have quite a way to go.

In other words, our mental abilities will change significantly as we get older but they aren't lost. Often they are replaced with changes and functions that will be more useful to us.

To summarise: there is no age at which we are best at everything – or even most things.

On average, you will reach your sexual peak in your 20s, your physical peak in your 30s, your mental peak in your 40s and 50s and at will be at your happiest and relaxed in your 60s.

Really though, the most important message is life is a series of ups and downs, peaks and troughs. For everything you end up mastering in life, there will be another challenge waiting for you around the corner.