I struggle with this for DH, who would live on poached eggs, smoked salmon and baby spinach given the choice.
Buttered leeks. Dead simple and tasty
I do a tea called ‘random fridge crap’. Based on a quick onion, mushroom, garlic base with either fresh (if they are randomly in the fridge going bad) or tinned tomatoes or passata. Sometimes a bit of chorizo, sometimes chicken breast, sometimes bacon. Chuck any other veg in that’s going bad, or a tin of green beans or sweet corn. If there’s cheese that needs eating, it gets bunged in the oven covered in cheese. If not, it’s with pasta as a sauce. Oh yeah and yoghurt or creme fraiche if there’s some there. Loads of veg in a simple tea.
Add mushrooms to anything saucy. Bulks it out and adds a veg.
Beans on toast - that’s a veg. Or beans, tomato and mushrooms with your fry up.
Carrot and cucumber sticks to graze on if you need snacks.
I also make a big pot of salad really simple - dice up cucumber, tomato, peppers and onion, add garlic, lemon juice or oil/vinegar, sometimes a chili) and grab a big spoon with tea, or box it up with a chicken breast for lunch. Lasts a couple of days and even DH will do the same and he’s a veg hater, but likes easy to grab food.
As others have said - soup. Curried butternut squash soup is a winner here.