stretch, loosen, open, relax, mention
舒 centers on releasing tension or constraint: stretching something out, loosening a grip, opening up, or relaxing. The 'mention' sense extends this idea to opening one's mouth to speak.
舒 combines 舍 (a building or to set aside) with 予 (to give or bestow), suggesting the idea of giving space or releasing, hence stretching and relaxing.
The left side 舍 looks like a house with a roof, and the right side 予 suggests giving. Imagine giving yourself space inside a house to stretch out and relax.
For ジョ, picture a person named Joe stretching after a long nap: Joe -> ジョ, and he loosens up completely.