From the time I started my career in professional football, fitness was fundamental to everything I did—including how I handled my finances.

Just as I didn't want to be someone who flamed out of the NFL after a couple of seasons due to injuries, I didn't want to be one of those guys who ended up dead broke after their playing career was over. And pretty quickly, I discovered that fitness and finance shared a lot more than that.

Both are about having the right mindset to take care of what's yours. Both also can be tracked by following a few crucial rules, or as I call them, key point indicators. These five points are some of the most important things I've learned over my career, so listen up.

1. Be Selfish

I talked about this in my article "Seven Secrets for Living Ripped Year-Round." Being selfish means dropping that mindset that says, "Fitness is vanity, because it's time away from your family" or whatever else you've heard. If you want to be the best parent, partner, and fitness freak you can be, you're going to have to spend time, effort, and resources to work on yourself.

Think about it: Who is more valuable to their employers, friends, and family? Someone who is dragging butt through life, or someone who is healthy, strong, and full of energy and confidence?

2. Invest Your Life, Don't Just Spend It

This is all a question of mindset. You can spend your time, or you can invest your time, which yields a return.

When you train, eat healthy, and make fitness-conscious choices, you're investing your time. That is going to get you one, two, three steps closer to your goal—the vision you have for your life. The small investments you make will exponentially compound over time.

When you spend your time, there's no getting it back. You're not getting anything in return but a momentary distraction.

3. Diversify Your Life

If you've ever met with a financial advisor, you may have heard them talking about diversifying your portfolio. The idea is the same in fitness: The more you focus on one thing to the exclusion of all others, the more risk you expose yourself to.

Don't put all your eggs in one basket. Don't only weight train or do just yoga. Find something you're passionate about doing, but spend time doing different kinds of exercise for overall wellness.

Perhaps because I come from the unpredictable battleground of pro sports, I'm not interested in just being strong. I want to be strong, flexible, healthy, and energetic. True diversification is taking a big-picture perspective of your investment and eliminating weaknesses. If you want to be in this for the long haul, make sure that everything is safe, sound, and fit.

4. Analyze The Costs

So it's Sunday night, and you've got 90 minutes to spare. You could spend that time prepping your meals for the next five days, or you could spend it on the couch watching Netflix. Both cost you the same amount of time. Which one will you choose?

Before you try to push me off my high horse, know that I'm guilty of it, too. I love television, but not at the cost of chasing my dreams. I know if I spend those 90 minutes wisely now, I'll get them back and more during the week. So is it worth it? Yeah, it's worth it.

But it's also hard work; that's always the tough part. If you have the mindset that nobody is going to work harder than you, I guarantee you will be successful.

5. Maximize Your Yield

What is yield? Yield is a result. So what are the yields of this lifestyle? More confidence. More self-worth. More energy. More focus. More success. More happiness.

Those are all things that we're after—but none of them are free. You have to ask yourself at the end of the day, "Did I invest in my life today, or did I spend my life today?" Because you only have 24 hours. How are you going to use it?