To roll over, or to and fro; to throw one's self about; as, a person on pain tumbles and tosses.
To roll down; to fall suddenly and violently; to be precipitated; as, to tumble from a scaffold.
To play tricks by various movements and contortions of the body; to perform the feats of an acrobat.
To turn over; to turn or throw about, as for examination or search; to roll or move in a rough, coarse, or unceremonious manner; to throw down or headlong; to precipitate; -- sometimes with over, about, etc.; as, to tumble books or papers.
Do the one thing you think you cannot do. Fail at it. Try again. Do better the second time. The only people who never tumble are those who never mount the high wire. This is your moment. Own it. Oprah Winfrey
Skateboarding teaches you how to take a fall properly. If you try to kickflip down some stairs, it might take you thirty tries - and you just learn how to take a tumble out of it without getting hurt. Bam Margera