I think people decide on different fitness routines and methods for only a few reasons.

1- They want to lose weight, body fat or get more muscle.
2- They want to look better naked or in swimwear.
3- They want to feel better.
4- They were told by their wife/husband/parter/doctor to get their shit together.
5- They get peer pressured into it.
6- It’s a social thing.
7- They want to win…to be better than the rest. “Winning” is a narcotic.
I think that given time, commitment and the right training environment, will at some point lead to the last reason on the list almost every time…
Imagine waking up one morning, looking at FaceBook and finding out that an old friend has tagged you in a picture from 10 years ago.
You smile to yourself at having not seen some old faces in a while. You reminisce about what a great time you had, and then you look closer at yourself in the picture and see a version of yourself that doesn’t exist anymore. You can only live on the memories of your athletic accomplishments of the past for so long before you realize your belly ain’t flat, your face is twice as wide and you get out of breath climbing a flight of stairs.
Men tend to be worse than women when it comes to actually doing something about this.
Most women generally tend to shame themselves into action quicker, whilst men will suck the belly in, puff the chest up and convince themselves that fat is muscle.
A friend – let’s call him Laurence – recently told me how he got into CrossFit.
An old school buddy of his was traveling around the world taking selfies, shirtless and tanned with muscles and bikini clad women.
In school, 10 years previously, Laurence was the stud and his friend was the ‘also ran’.
Laurence looked down at his now massive shirt and pants and said to himself that it was time for a change…
3 years later and Laurence looks like a different human to his former self.
He’s happier, attracts more attention from people – which is great for him because he likes being the center of attention, and he doesn’t feel like he’s about to pass out every time he has to walk up a few steps. Far from it, he’s better described now as an athlete and competes whenever he can.
His friend is still taking selfies in exotic locations with bikini babes but everyone is happier.
Being told to get your shit together or face the consequences is possibly the biggest motivator.
I think my wife telling me to sort my crap out is more of a push than my doctor. After all – “that look” from your significant other is something you don’t want to see too often.
Many years ago I once had a fat doctor tell me my blood pressure was too high and that I needed to go on medication to get it down.
I wanted to punch him in the throat. All he needed to say to me was that my numbers were not good and that I needed to sort my shit out by eating differently, removing stress and starting an exercise plan.
I refused the medication and instead told him I’d sort it out through lifestyle changes. 3 months later when I returned to the fat doctor I was in the normal range for blood pressure.
A punch to his throat to celebrate not taking drugs.
I’m much older now and significantly more athletic than I’ve ever been and am hungry for more.
I’m also determined never to have medication prescribed to me when there is an option to fix my self, through smarter choices. 
A drug might work instantly but once it wears off you’re back to square one, wanting to throat punch.
Anyone who gets peer-pressured by family, friends or loved ones into doing CrossFit should really be thanking the person who got them into it.
Married men know all too well about doing something slightly unwillingly to keep the peace and it pains me to say that it’s a proven fact that working out alongside someone you know/love/work with..whatever results in a better outcome for both parties. 
Something about the genetically engrained competitive nature of human beings makes most of us push a little harder in a group setting.
Initially there might be some reluctance of course, but for those who stick it out he pay off is far greater in many ways than you may initially realize. Plus, who wants to listen to another conversation about WODs, barbells and AMRAPs again without knowing what the heck they’re on about.
It’s also a well known fact that you sleep better knowing that you beat your wife/husband/ significant other/ co-worker at a workout that he/she was ranting about being so good at beforehand.
Extra smug points achieved.
Of course it doesn’t have to be CrossFit that starts a body/mind revolution, but it’s proven to be the most effective Strength and Conditioning program around. It’s not the same repetitive workouts everyday and it’s not telling you how many calories you burnt.
Remember this: It’s WAY more impressive to see a 50 year old woman doing pull-ups in a CrossFit gym than it is to see a 25 year old woman furiously sweating away on a spin bike…
We’ll take the credit that we deserve for making better humans whenever we can.