This answers my musing that you can become your own machine.
Yesterday I put in a lot of work re-digging in a stone border for my two annual vegetable beds. I can't say every second of it was tranquil work, but a good deal of it was. The most important thing, I think, is breathing. If you can stay oxygenated, you are far less of a fool. If you can still your mind a bit, your mind opens to your surroundings. After all, I was working on a great day with bird song around me. I was working in a beautiful garden that I was only trying to make beautiful (okay, trying to make one of the ugly spots significantly less ugly)
To get the deep breathing, and a stillness of mind, I found it helpful to be more deliberate in my motions and focus on a flowing shifting of weight, like in Tai Chi. And this is how, from time to time, I mediated in action.
I understand this thought is not original. We know all about zen in the art of ____, but sometimes everyone needs reminding from time to time. This is my reminder.