I am writing this from a vague memory but the overall theme of the cartoon I remember very well. It aired before 2000 but definitely after 1985.
It's a cartoon about a boy who is given a ball or something with a piece of string sticking out from it by an old lady. This boy who is supposed to go to school is resting on some piled up hay and talks something to his friend or girlfriend about how boring school is or he doesn't care much about school and how he wants to skip it.
The main point is he is not happy with his current life and wants to jump ahead in time. So this old lady comes out of nowhere and hands him this ball with a string. She tells him each time when he wants to jump time just pull the string out a little and it will be done. The first time he pulls the string he jumps into a time where he is dating this friend. Again he pulls then he finds himself married to her, he pulls again to find that he is middle aged or something and he pulls it finally to become an old man. Then he realises that he is not supposed to do that and wants to go back to being a kid. He wakes up as boy in the same pile of hay and realise all that was a dream and is happy to go to school.
Again the above is a vague outline of what I remember. The boy, the pulling of the string from the ball, the time jumping, him being old and waking up as if it was a dream is clearly in the memory.