When you die you forget. Death is a sleep, a forgetting. You forget about your previous lifetime. The essence of your being is the same. But at death, the personality dissolves
The burden borne by mankind is a heavy and a crushing thing. The word Jesus used means a load carried or toil borne to the point of exhaustion. Rest is simply release from that burden. It is not something we do, it is what comes to us when we cease to do. His own meekness, that is the rest.