Worth noting, perhaps, is that the main reason people fail to open jars is not due to a lack of grip strength, but due to a lack of friction. If you have a stubborn jar that you cannot open, put on a pair of rubber dish gloves and try again, and I think you’ll be surprised at how easily a previously-unopenable jar magically pops open. This method has literally never failed me.
Worth noting, perhaps, is that the main reason people fail to open jars is not due to a lack of grip strength, but due to a lack of friction. If you have a stubborn jar that you cannot open, put on a pair of rubber dish gloves and try again, and I think you’ll be surprised at how easily a previously-unopenable jar magically pops open. This method has literally never failed me.