"Your AirPods can get up to 5+ hours of listening time or 2+ hours of talk time on a single charge" Source: A
This means you can go for a nice long jog or exercise without bringing your charging case with you. Just take these neck strap + Earbuds holders + Watch band attachment with you to provide extra protection against dropping or losing of your AirPods earbuds.
Flexible, comfortable AirPods Ear buds neck strap for jogging and exercise.