Four years ago I picked up a belt at a race. It has toggles to attach a race belt, but also a nice size pocket that will fit my cell phone and keys, or snacks; along with some elastic slots along the sides that are perfect to hold onto a gel. It is water resistant.

I use it for just about every run except in winter when I have my running jacket that carries what I need. I love it! There are a lot of options on the market, but I can attest to this one, called the Spibelt. (They have different variations, hopefully all wonderful. The one I linked to looks closest to the particular one that I have).