There's a trick I've been using for ages for getting jar tops off easier.

Remember 'crown seal' bottle caps? You used a bottle opener that lifted the cap, the type that looked like a little sharpened flat hook? Well, you often find that sort of opener on some of those screw type can openers.

You merely get that hook under the lip of the jar lid, and ease it up - there is usually a lot of leverage available, so not much force is required. When you hear the jar lid seal break (hiss), you can then remove the jar lid with far less force, as you are not fighting the 'vacuum' seal, just perhaps where the rubber was compressed, the first time.