If all you do is run, HIIT, bike, or just do traditional high intensity CrossFit workouts you are missing out on a huge part of training that will increase your lifespan. That type of training is strength training.
By no means am I saying that the other types of fitness activities are bad. I am just saying that if you never focus on getting stronger you are missing out on a HUGE part of what will keep you alive longer and here is why.
I will compare your strength to a cup filled with water with a plug in the bottom. The fuller your cup, the stronger you are, but as time goes on the plug starts to leak. This is the same with strength. You will eventually hit an age where your strength is no longer increasing but you are just fighting to hang onto what you have. When the plug starts leaking you do everything you can to get it to a slow drip but the cup eventually loses water faster than you can fill it up. This is the same with your strength as you age. Eventually your strength training is to maintain as much muscle mass and strength as possible rather than to get stronger (Don’t worry, this is what happens to all of us as we get older. The good news is it doesn’t have to happen to you until your in your 70’s or even 80’s). The point of this analogy is the stronger you are now the longer you can fight off the loss of strength as you age. Being strong might not matter to you now but I am pretty sure no one wants to be put in assisted living because they can’t get on and off the toilet on their own because they are to weak to do so.
I workout so that means I can eat what ever I want, right? Sorry, but that couldn’t be further from the truth. Looking at this from the caloric side, if you workout for 60 minutes a day and have a desk job then you’re pretty sedentary the other 23 hours of the day. So your caloric intake for the day should probably be around 2200 calories. But if you decide that eating a frozen pizza and having a few beers for dinner is fine because you went to the gym that day you just bumped your calories up to about 3900 which is 1700 calories more than you need.
I hate to say this but the saying “You can’t out work a bad diet” is true. If you think of your body as a car and you just got a tune up you wouldn’t go and put alcohol in the gas tank, would you?! Food is fuel for the body. The food you eat makes up the building blocks of your body. Your body is looking for proper nutrients and putting crap into your body day after day will not get it done. It’s really easy to over eat when you’re only active 60 minutes a day, you lead a sedentary lifestyle, and eat low quality food full of calories that lack nutritional value (FYI, if your body is not getting the nutrients it needs it will continue to tell you that you are hungry). You truly are what you eat. So which would you like to be? A greasy piece of pizza or a lean chicken breast?