Simply brace the lipped side of the speed square against the edge of your board, pencil a line up the hypotenuse of the speed square, and voilà! You have a perfect 45-degree angle for easy corners.
Hold onto the bars or edge of the chair, straighten your legs, and lower your body until your elbows are at a 90-degree angle. Push back up to the starting position. Do three sets of eight to 10.