I’m not a fan of pants, shorts, or “bottoms” that are secured with a drawstring. For me, drawstrings don’t work well, primarily because any kind of weight in the article’s pockets defeats the “up holding” ability of the string.
I’ve tried spring-loaded drawstring stoppers, like used on sunglasses straps, but they don’t work well for me either.
These Sgt Knot Wheeled Cord Locks are much better. I was skeptical, but found they work great. I gather from the company name and info there is some sort of military connection happening, but I’m pleased to report that if you have comfy pants or shorts to wear, they will serve you well too.