How Much Gravity Do You Actually Need?

Earth is 1 G which is our normal but hard on the knees. Earth orbit is 0 G which we know causes problems for our bodies over time. It's actually called micro-gravity, if you knock a cup off the counter it will take three years to hit the floor. The Moon and Mars are less than 1 but more than 0. If I could live on the Moon, I could still have a cup of coffee in the morning, jog 30 Km without ruining my knees and maybe finally bench 180... I wonder if there was a study? Maybe the Russians did one and never told anybody!