I find it quite difficult but mainly because I don't really eat between meals that much so having fruit or veg as snacks doesn't really work for me. I can't drink too much fruit juice and prefer water anyway (that at least I do get my daily amount of).
Don't get me wrong, I love my food and can eat quite a lot at actual meal times. Our dinners nearly always consist of peppers, onions and mushrooms in some form, (base for pasta sauces, currys, stir frys etc) and I really like green beans. I also tend to eat soup for lunch which usually counts or adds to my veg intake and I have fruit for pudding at lunch time, I also try to eat fruit at about 3pm but if I don't feel hungry then I often forget. I think if you actually focus properly on it then it is probably quite easy to do but it's not something I get too worked up about really.