Some suggestions that have helped in our house, find out what they will eat rather than try force what you can stomach on them.
Our 8 year old struggles with carrots peas or salad but is partial to sprouts (bleh), parsnips, butternut squash (also bleh) and occasional broccoli.
Also started a points system (1 for a pea, 10 for a sprout 20 for an apple etc. Suprising how motivating that can become when the older sister tucks in to cabbage (10pts) etc.
never gets any easier though.