Hi @Dog_Jogger !
@REI-JohnJ provided some awesome ideas to get you started with finding the right lumbar pack. I've got a couple more suggestions:
Nathan VaporKrar Hydration Waistpack: This is probably the largest belt-style running pack we carry, and the only one that has extra cinch points to secure your contents.
FlipBelt Zipper: You could probably get away with a smaller belt-style pack like if you have a thin layer that packs into itself and the ability to carry a phone in a pant pocket or seatpack--they're probably too small to accommodate a layer, phone, and softflask.
Hopefully we've given you some ideas that have a secure fit on the body, and shouldn't move too much while running. But if you happen to visit Alaska to go running with @REI-JohnJ , you'll probably need to switch to a vest instead to carry the bear spray, too!