I have one of those clip-and-seal type lunch boxes, which I stuff full of salad things.
As a base, I usually chuck in half a tin of chickpeas and some chopped up chorizo. Then slice up some mange tout, sugar snap peas, baby sweetcorn, or pepper (usually two of this list). I dress this with olive oil and balsamic vinegar, plus pepper and some dried herbs or chili flakes. Then, stuff the rest of the box full of salad leaves.
I occasionally use sesame oil and soy sauce as a dressing, or skip the chorizo and chuck in a hard boiled egg. I've managed to consistently stick with this for the last few months without getting bored.
Like samuri, I'm an Adonis who doesn't need to lose weight, but I've found having this for lunch offsets all the biscuits, donuts and mince pies I eat on evenings and weekends