"so [Jesus] got up from the meal... and wrapped a towel around his waist. He poured water into a basin and began to wash his disciples’ feet, drying them with the towel that was wrapped around him." -John
The foot washing, recorded in the gospel according to John, allows us a window into the character of Jesus Christ.
Christ, by his actions, made it very clear that He would not expect anything from his followers, that he was not willing to do himself.
This act models humility to us in application to helping others and by doing acts of service or kindness.