Football is a game played with two feet. Sometimes a head. A thigh. A shoulder might make an appearance every now and then. A shin, if someone misses their aim. A bum when that goalmouth scramble bounces in the wrong direction.
But for all of the physical and technical qualities needed to win a match of football, it is often the thing between the two ears that actually determines the victorious team.
The brain. The mentality. A winning attitude that is subconsciously instilled and entrenched into individuals and teams. This is what often tends to yield the victor in sport.