Add a bit of spinach to your shake!
Tee hee! Susan acknowledges something I've been doing for a while! My trick is to buy frozen spinach (the kind in pieces or blocks) and to blend one block or a couple of pieces of this into my shake. You can barely taste it, it cools and thickens the shake and gets you an extra serving towards your five-(or seven)-a-day! Plus - frozen spinach keeps much better than the fresh stuff and is probably just as nutrient rich, if not better!