Anyone can get motivated for a short period of time, especially if you have a very specific reason or goal. But motivation doesn't last and if you rely on it solely to get you through the ups and downs of your fitness program, you'll likely end up failing.
Much like willpower, motivation is a finite resource, and the rush of adrenaline you get after watching Rocky 3 or watching The Iron Cowboy doing 50 Ironman Triathlons in 50 days, will wear off pretty quickly.
Instead, I propose using two things to help you stay focused on your goals and that's inspiration and habit.
Inspiration is the thing that lights you up inside and resonates with you on a deep emotional level. Maybe it was your father dying in his fifties from diabetes and you're scared it might happen to you.
Maybe you've always been the "fat guy" and it's shaken your confidence in yourself. Or maybe you're a former athlete and want to feel strong and athletic again.
There is no right answer for this and you'll have to look deep to find what truly inspires you but once you find it, you can use it to keep you pushing forward even when you really, really want to stop.
I've spoken with hundreds of men about this and sometimes inspiration is deeper than one is willing to look. And in that case, I'd tell you to rely on good old-fashioned habits.
Habits are nothing more than the things you do on a day to day basis and unfortunately, many of ours aren't conducive to optimal health.
Most of us have habits that have been part of our lives for a long time and things like eating snacks late at night or drinking that early morning Red Bull are very hard to just stop cold turkey.
In my experience, taking small steps is the best approach and replacing one unhealthy habit with a better one every 7-14 days is a great start. The key is not to overwhelm yourself with trying to totally revamp your entire lifestyle because that always almost ends of crushing failure.
Take it one day at a time and remember, you're in this for the long haul.