For me it's plumbing. Flush the toilet, get rid of waste through a hidden underground network and it just works in the middle of a city with millions of people

For me it's plumbing. Flush the toilet, get rid of waste through a hidden underground network and it just works in the middle of a city with millions of people doing it every day. It also gives me perspective of the enormous debt I owe to (hundreds of) thousands of people "just doing their job" for me to be able to sit where I am and do my part of it. Just from the vantage point of my office chair, the things that surround me have been touched my so incredibly many people during their production and delivery to here.