I'm there with you Alex on watching people at the gym. I once went in and did an entire powerlifting routine with four exercises, about 5 sets per exercise, and I was done in the span of maybe 45 minutes. Meanwhile there was this older woman (with a really creepy smile/stare) who was on the elliptical when I got there, and still on the elliptical when I left, and came back for my forgotten water bottle. She's probably still on it for all I know.
I like HIIT, I especially like doing it with a jump rope. You can even toss in a super-hard interval in the middle with doubles (or triples if you can), just varying singles speed on the rest of the intervals. I suppose you could do this just jumping around in place at different paces, but at least with a rope you don't look like a tool.
1) eat real food - more vegetables, moderate meat, moderate fruits, less grains, less sugar, less vegetable oils.
2) exercise - moderate intensity cardio, sprinting, heavy lifting, dedicated stretching and mobility.
3) live - relax, de-stress, meditate.
Disclaimer: I'm not professionally qualified to make any formal recommendations. I've just done my homework and I'm my own guinea pig. All of my data, unless otherwise cited, comes from a sample size of n=1 (me).