One thing I've never been good at is eating very healthily, but I work out a lot, cycling 15 miles a day and circuit training or weights most evenings. However, I'm struggling to lose that last bit of fat around my abdomen, which is really bugging me seeing as I do so much exercise. I'm assuming this is coming vastly from my diet. Looking more closely at it, I'm eating a lot more sugar than I should. I need to eat carbs a lot because I'm a rower, and they are critical fuel for the sport. But when I'm at work, I don't get time to make proper lunches, so always end up eating crappy food that I know isn't particularly good for me. Can anyone recommend any quick things that I can pick up from the supermarket, that I don't have to cook, that can help me reduce the amount of sugar in my diet?
There's really no easy way to have very low body fat. For me anyway, when I start getting near 10%, my willpower goes out the window. But I also don't care that much and 10-15% is fine for me. It's just not worth it (to me) to shave those remaining pounds off knowing what I'd have to give up.
If you find someone with a lot of muscle mass that's sub 10%, you'll find someone who's done a lot of lifestyle modifications to make that work. It's a bit age and individual dependent as well.
Consider looking into a keto diet (http://en.wikipedia.org/wiki/Ketogenic_diet). Long term it's the most successful dietary habit I know of.