Most of us are not short of humility in theory. We are short of it in the specific.
The foot washing in John 13 was not a principle Jesus commended. It was a basin, a towel, and the worst job in the room, done by the person with the most status. That is what makes it impossible to be vague about.
So get specific today. Name the unglamorous thing in your own life that you have been leaving for someone else, or avoiding because it feels beneath you. Then do that thing. It will probably not feel spiritual at the time. It will feel like work. That is the point. Jesus did not hand us an idea to admire. He handed us an example to follow, and the towel is still where He left it.