Actually I did look at my health as a project a few years back. I dropped from 240 lbs to 180 lbs in six months or so and have been in the best shape of my life. I pretty much pictured myself grinding like one would do in an MMO (I used to be real into FFXI, so doing repetitive boring shit several hours a day is right up my alley) while working out, jogging, or min/maxing when choosing the right foods to eat and my fitness schedule, as nerdy as that sounds. Looking at the way I handle a lot of things in my life, I do treat a lot of my issues and goals as "challenges" the same way I would in a game. It helps me get a better focus on the situation.
My phone is for checking email, browsing the internet, listening to the music and, well, making a phone call and with all of that my phone can barely make it to the end of the day. I leave gaming for a dedicate gaming device. And don't forget that Vita might have cheap, disposable apps like Androids and ios do so casual user should be able to enjoy killing their time on Vita too.
Well a-holes look down on you if you're an adult and they find out you play games. They don't care as much if you do it on your phone though, probably because they're guilty of playing games(!). But yeah, gaming usually sucks on non-dedicated devices, the only game that worked okay for me with touch controls is Ilomilo, and that would be better with actual buttons (except the pinch zoom control was cool). It really depends on the phone in terms of battery life. When I had a low-end Android phone that almost nobody else bought it was a POS for gaming and phone tasks (except emulation - ironically - until Google pulled the app from the app store). Now I have a Windows Phone and the battery lasts ages with WiFi left on, every game is guaranteed to work, and the phone stuff is good. But there's still no damn buttons.
It's funny you say a-holes look down on gamers for using a dedicated portable gaming device. Sad how so many gamers look down on the ones who can derive fun from smartphone games. I'd figure that coming from an industry that has been kicked in the ribs by the masses for going on 3 decades now, gamers would be a little more open to other gamers' tastes and perspective.