The Anker SoundCore Liberty Air 2 are great headphones for fitness use. Once you find the right sized silicone tip, they feel quite stable in your ear and will likely be able to withstand most workouts without falling out. They're also fairly comfortable and have a decent touch-sensitive control scheme so you can change your music without taking out your phone. They're rated IPX5 for sweat and water resistance, though we don't test for this.