Opening the book…
The last few inches of a rip cut are where hands get hurt, because that's when your fingers come closest to the teeth and the offcut wants to bind. A push stick puts a cheap piece of wood between the blade and you. If something goes wrong, the stick gets chewed up instead of your hand, and a mangled push stick is a story you laugh about, not one you tell in a waiting room at midnight.
Keep two push sticks hanging within arm's reach of the saw so you never talk yourself out of grabbing one. Start using it well before the danger zone, around six inches from the blade, not once you're already crowding it. For narrow rips, use a push stick in each hand, or a push shoe that holds the stock down as it feeds. Make a handful from scrap plywood, and when one wears out or splinters, just cut another.
On wide, long stock where your hands stay far from the blade the whole cut, a push stick can feel clumsy and a firm flat palm may control the board better. Judge by distance to the teeth, not by habit, and reach for the stick the moment the cut narrows.