I don't want bulk up either, I want to be lean but strong. At 5"11, my max weight is 170 and ideal would be a ripped 165. I'm currently 165, but could be a bit more cut. I don't measure my bodyfat %, or my lean muscle mass or anything else. Just be fit and healthy so my muscles, bones and body overall works as it should when I'm older. Not sure if I'm a little paronoid here, but I would be more concerned about putting on serious mass when young, and having creaky joints, rolling flab or man boobs when I'm older. I also didn't even start doing any workouts until I was 30, though played competitive sports all my life.
If I want to lose weight I run and cycle. I find for me that the perfect amount to not put on weight is to run 40-50km/week over 3 runs spaced 2 days apart. I cycle on the off days, with 1 day of rest per week where I do nothing but rest. My runs are usually 60-120min and they don't have to be fast runs, but consistently paced or interval based. In addition, I'll do a gym workout every day for at least 30 min, where I mix a variety of bodyweight exercises with weights. The problem with enjoying running for me is in not working out my legs enough (because sore legs are hard to run on) and it then leads to a weaker trunk overall and leads to injury during running. I try to make up for it by lots of core workout - but that doesn't make the most sense.
If you smoke, stop. I did for about 18 yrs and giving that up had a big impact on energy levels. When I started running a few years ago, I could last max 5minutes - it was pretty sad.
Regarding diet and staying within the context of being lean or cut, I think it's simple. Eat healthy. Whether you eat meat or not, keep your diet clean, light and balanced. I used to eat way too much meat and way to much sugary drinks and processed foods. Personally, I stopped eating all meats and drinking dairy milk about 5 years ago, and increased my intake of all kinds of nuts, green leafy veggies, legumes and fruits. No processed foods at all anymore. I try to roughly balance my protein, carbs and good fats at 1/3 each. The human body needs these things to sustain itself on so many levels. For general weight loss or body health, minimizing protein or carbs or all fats is one of the most confusing things I have ever heard. It's so unsustainable it's ridiculous.
Someone posted earlier about doing grocery shopping only around the perimeter of the grocery store - some of the best advice in this thread!