[mass55th]

"I am a 71 year old guy and I have to water heat the jar predominately jelly and leverage my weight to open sealed jars."

I smack the jar lid on the counter, or whack the lid several times on its edge with a tablespoon. They open every time. I like violence, so that's what this 69 year old woman does.

[faucetman]

“I whack the lid several times on its edge with a tablespoon”

I smack the jar lid on the counter, or whack the lid several times on its edge with the back edge of a table knife.

[RipSawyer]

I guarantee that jar was preopened and then the lid was put back on with ever so slight a twist, just enough to keep it from being obvious.