Reacting keeps you one step behind. Reading the play puts you one step ahead.

Reacting means waiting for something to finish before you move, which builds a delay into everything you do. Reading means watching the setup and moving while it is still forming. The gap between the two is not speed of body but where your attention was pointed a moment earlier.

Pick one situation that keeps catching you out. A rush at work, a particular argument at home, a moment in a game. Watch it three times without acting and note what always happens just before. Then move on the signal instead of the result.