OK, this is supposed to be a simple thing you can do to make an easy difference - saving, time, money or the earth. This one actually saves all three!
Save and use meal leftovers. Really - that simple - of course for me sometimes the key is to actually USE them!
Most of our leftovers become lunches. Sometimes they are a bit odd when we are really cleaning out although Joey calls it "Leftover Celebration!" The worst part about using up lots of leftovers -- lots of dishes.
Produce that is started to "go" gets chopped and put in the freezer for use in soups, casseroles, etc.
I challenge you to save and make use of those leftovers - get creative!