It's a well-known fact of life that you can only get out of it what you put in. The harder you work, the more rewards you'll reap. And one person who knows that you've got to make sacrifices to succeed appears to be Mark Wahlberg.
Yes, the Hollywood superstar formerly known as Marky Mark makes some real sacrifices to keep himself in tip-top mental and physical shape and, at 47 years of age, his efforts certainly seem to be worthwhile.
However, the reason he looks so good is because he keeps to a frankly ludicrous routine of exercise and regimented lifestyle management. Sure, you'll live longer, but at what cost?
During an Instagram Q&A session, Wahlberg revealed what a typical day looks like for him. See if you think you could keep up with this.
The day begins at 2.30am, which is when most of us crawl into bed. Not Mark - he's up and ready for the next assignment, which is half an hour of prayer, followed by his first meal at 3.15am.
Then it's off to the gym until 5.15am, before a shower, half an hour of golf (still only 7.30am) and a snack.
It continues in this frantic fashion throughout a day that also includes cryogenic chamber sessions and numerous meals. There's even time to pick the kids up at 3pm, before heading to bed at 7.30pm, only to get up at half two and do it all over again.
It's difficult to tell whether this is ridiculous dedication, or just ridiculous.
I mean, it's working. He looks better at 47 than most of us will do, so fair play to him.
However, it doesn't sound like a great deal of fun - 7.30am golf aside - and it requires an utterly incredible amount of fuel.
Yes, perhaps even weirder than his regime is his diet. It sounds like it should be impossible to consume this amount of food and spend any time away from either the dining table or the toilet, but Marky Mark perseveres.
In the Instagram Q&A he said: "I start out with steel cut oats, peanut butter and blueberries and eggs for breakfast.
"Then I have a protein shake, which is a Performance Inspired Nutrition vanilla latte shake, three turkey burgers, five pieces of sweet potato. That is at about 5.30 in the morning."
While eating burgers at five in the morning isn't so alien to many of us, it's not usually the first meal of the day. Personally, I like to fall asleep in it and wake up covered in chilli sauce.
It doesn't end there, though.
He continued: "At 8.00, I have about 10 turkey meatballs.
"At 10.30, I have a grilled chicken salad with two hard boiled eggs with olive, avocado, cucumber, tomato, lettuce.
"And then at 1.00, I have a New York steak with green peppers.
"Then at 3.30, I have grilled chicken with bok choy ... At about 5.30-6.00, I have a beautiful piece of halibut or a cod or a sea bass - some sort of white fish with some vegetable, maybe some sautéed spinach."
By that stage, it's nearly time for bed (7.30pm) so he calls it quits.
Of course, he is working out an extreme amount to maintain this diet. If you or I did it, we'd just end up weighing about 300lbs. Basically, unless you're Mark Wahlberg, don't do this.