I hate wasting food, and I know I’m not alone in that.  So when my lemons are starting to get past their prime, I zest them, squeeze the juice into an ice cube tray, and freeze the whole thing.  I put the zest into a small baggie right in with the frozen lemon juice cubes.  I kind of flatten the zest in the bag so that it’s easy to break off a small amount when I need it.  You’ll never have to throw out lemons again! 🙂