I recently picked up the new book by coach Dan John, Never Let Go, and so far it's very educational as well as a fun read. Dan has been training since the late 60's, and is the current National Champion in his class for discus.
In the book there is a section regarding top ten tips for fitness/long term health. Dan is a no bullshit kinda guy, and he's trained a ton of top athletes as well as kids (his day job).
Anyway, one of the tips is to have some passion. But perhaps not in the sense you are thinking, and certainly not in the way corny motivational speakers blather on about.
He's talking about the Latin root of the word, which means to suffer. To get anywhere meaningful in your training it's necessary to do things you hate, and that are really hard.
Think about it. Nobody gets overweight by doing things that are hard, or that they don't like, or eating things they don't like. If your goal is to drop 20lbs or do a double bodyweight deadlift it's going to take considerable work, and yes even some suffering (mild suffering, admittedly). Training isn't THAT hard. Your going to have to develop good nutritional habits and create a sustainable lifestyle congruent with your health goals.
If you aren't willing to suffer a bit then you might as well join the people watching TV while "working out" on the treadmill. As Dan says don't mistake sweating for hard work. You sweat in a sauna too and it doesn't mean nothin'. Hard work is lifting something until you can't do for another rep, or until you HAVE to stop.
But be careful because training like that can be addictive, and soon you might turn into one of those people that doesn't mind showing off your hard work.
By the way one of the best workshops I've ever attended was by Dan John on the subject of hip mobility/squatting/Olympic lifts.
Watch the entire workshop on video here.