Theory
Zugzwang — being forced to move when every legal move worsens your position — is rare in the middlegame but central to endgame technique. Opposition is the most common way to force zugzwang onto an opponent: by occupying the right square at the right moment, you leave the enemy king with only bad options.
Direct opposition (kings facing each other, one square between them, same side to move) is the simplest case, but distant opposition and diagonal opposition follow the same underlying parity logic once you’ve internalised it. This is one area where a bit of counting genuinely replaces the need to calculate every line.
Model Games
Composed endgame studies teach this better than games, since master games rarely reach the purest form of the position. Work through basic king-and-pawn opposition studies before trying to spot the pattern in a real endgame — the recognition needs to be automatic under time pressure.
Practice Positions
Set up a basic king-and-pawn vs king position where the attacking king must win the opposition to queen the pawn. Practice from both the winning and losing side until choosing the correct king move stops requiring calculation.