'you also ought to wash one another's feet'. To humble ourselves before the Lord, especially when it means discarding our desires in preference for His will can be hard sometimes. To take the lower place in relation to our brother is more difficult still.
There will always be those whom we greatly respect and whose feet we should count it a privilege to wash.
But it is with those our equals, or with whom we are trying to establish parity, or with whom we do not easily get on, that the 'washing one another's feet' becomes hard.
Yet any difficulty or embarrassment really originates from our unwillingness to treat others as better than ourselves. We can think we are more important and find our own uprightness to be unbending. But Jesus set an example and by it there is no mistaking what we ought to do.