What made you decide to get fit?

So I was reading a thread earlier about when people realise they need to loose weight and it got me thinking, what made other slimish people decide to get fit? Also there was a lot of talk about "realising you are fat" and that kind of makes me wonder if it is possible I or others are closeted fat people, I'm not so worried about this because it is already a legit struggle to find small enough clothes (I am an Australian size 6-8 american 2-4), anyway after my two pregnancies I "bounced back" to my average weight pretty quickly but where I carry it is different, and honestly I am vein as hell so the decision to get fit is an aesthetic thing for me. But as I get further into it, it has become more about being strong. So why did you decide to get fit? When did you realise you should? And how do you stay motivated?