Those who say that age is a state of mind are young, delusional, or smoking something. Either that or they’ve been roped in by a ludicrous stereotype of how people of a certain age are supposed to act, which of course is nonsense.

In any case, there’s an epidemic of magical thinking these days. People seem to think they can just blink their eyes and alter reality. Everything’s a state of mind. Entrepreneurship. Leadership. Happiness. Age. What a load of entitlement BS. Everyone wants what they want without having to actually do anything.

If you don’t own a real business, you’re not an entrepreneur. If the only creatures that follow you are on Twitter or have floppy ears, you’re no leader. If your reality is miserable, I doubt if you’re going to be very happy.

And not to burst your bubble, but if you’re 42 years old, you’re 42 years old. You may not have 42 rings like a tree, but those years have left their mark on every part of your being, just the same. If you’re alive and moving significantly slower than the speed of light, time passes for you as it does for every living thing on Earth.

Now, if you want to be more active and healthier than your years would seem to indicate, that’s a different story. And while that may start with an idea, what it really comes down to is serious discipline, physical activity, and control over what you put in your mouth on a daily basis.

I’m reminded of a lunch with legendary venture capitalist and former Intel executive Bill Davidow at a Palo Alto sushi restaurant. I talk about it in the book. Thinking we might both be runners, I asked what he did to stay in shape. “Steve,” he said, “You have no idea how much work it takes to look this good at my age.”

Indeed, that was more than a dozen years ago and, while I’m still quite a bit younger than Davidow was then, I definitely have a more intimate understanding of what he was referring to. Once you reach a certain age, everything starts to wind down at a faster rate.

Your mind may think and feel the same but your body has other plans. You may have good genes, but everyone’s DNA is encoded with a clock that goes tick, tick, tick, just the same. And at some point, the ticking stops.

Don’t get me wrong. I’m not saying there is no mental component to looking, feeling, and acting younger than your years. Of course there is. But all that does is motivate you to do all the physical things necessary to actually keep you young, so to speak. You still have to take care of your body … and your mind.

It isn’t rocket science. Like anything in life, you get out what you put in. If you want to stay healthy, you’ve got to exercise, eat right, and see a doctor when things go wrong. If you want to be happy, you’ve got to make good choices and enjoy the ride while you’re here. And if you want to make money to pay for stuff, you’ve got to do the work.

Even if you do all that, there are no guarantees. Like it or not, shit happens. But one thing’s for sure. You have to take life as it comes. You’ve got to face reality, not try to sugarcoat it or sweep it under a rug of positive psychology or utopian thinking. Your neurons can only do so much. The only way to change anything is by actually doing.