Create an Animation - Video Clip

I need a 30 second animated video clip. 1st part (8 seconds) person trying to push a boulder up a hill. 2nd part (10 seconds) person gives up and stops pushing before he gets to the top. Then the boulder slowly starts to roll back down the hill, rolls over the person, then the boulder starts to pick up speed rolling back down to bottom of the hill. 3nd part (total 12 seconds) person pushing boulder up the hill, gets to the top, then the boulder starts rolling down the other side of the hill, slow at first then starts to pick up speed. Part 1 and 2 can be combined into one clip and part 3 can be it's own separate clip. Or you can combine all 3 parts into one clip and I can split them myself.