>Surprisingly, I found myself in a meditative mindset while polishing stuff or cleaning things very diligently.
That's no surprise at all, you are doing the same thing, whether you polish something, perform some tai chi routine, pray 3 times a day, or sit still. You are channeling your mind into dutifully performing some task, those are activities that require you to put all your concentration without spending much thinking or rationalizing. I have a theory that people watch so much tv because it induces a sort of meditative state, which is probably necessary in human life.
I think it is closely related to the act of rituals, in having some task to focus on and narrowing your thoughts through some definite activity to keep it from wandering.
As I said, I don't think meditation is necessarily sitting still, and there are actually a lot of different methods, one of my favorites is clay modelling. Japanese buddhism is aware of this, as seen in the traditional Zen activities such as: archery, calligraphy, ikebana (flower arrangements) and the tea ceremony. Tibetan monks do throat singing, and shaolin monks do martial arts. They are all a form of meditation.
I'll go one step further, I am inclined towards Chan buddhism (chinese version of Zen). I remember two things that appealed to me about it:
The idea that "The Way" (to spiritual enlightenment) can be walked by anyone at any time, it could be on your day trade, for example if you're a carpenter, your job can be your form of meditation.
The second is related, it's an anecdote I read when someone asked something to a japanes carver and he said "The buddha is inside this block of wood, I have to be very careful not to damage the buddha".
I consider Tai Chi one of the best forms of meditation for several reasons.
To wrap up, here's a video with a related idea that I expressed here, it is about acting, but hopefully you'll find what I was trying to express: https://www.youtube.com/watch?v=mQgZjRf-xmY