I don't want you to think that I am suggesting that you shift your "focus" from one activity to another, because that is ultimately is as same as a typical meditation routine. You are shifting your focus from whatever you were doing, to your focus on sitting idle and doing typical meditation.

That's not what I am suggesting with the dishwashing example. The meditation I am describing does not ask for you to focus .... instead, it asks for you to be "aware" and "be in present".

Here's the difference and here's what you can potentially gain:

When you are in the present washing dishes, you are training your mind to not be in the past and/or future. So now, if your mind is in present, than it does not matter if you are washing dishes or singing or dancing. The point is, that in present, you are closer to your true self and in present, you are more alert to the reality.

The mind constantly makes you wander either in the past or in the future and we generally don't and cannot stay in the present.

The example of doing your favorite activity (like running, exercising, singing, dancing etc) is important here because it is in these activities where you derive a whole lot of satisfaction and contentment for yourself. It has also been established that athletes usually find loosing themselves in their games at the moment of transcendence and we (the audience) have seen above-human or super natural acts come out of those moments (there is another subject of what audience derives out of watching such events, be that sports games, a movie, a concert etc, etc).

Hope you're following.

EDIT: Perhaps more to the point, many of the useful decisions or notions that might have arisen from thinking about the future or the past while washing dishes tend in my experience to arise more or less of their own accord, in their own time. Much of the mind tends to think itself once you let it.

I can't wait to do the dishes when I get home today.

Right, and I would suggest that there are no failures here — just notice what is going on in your mind, without judging it, and then gently bring your attention back to the breath. As we practice this over time the mind will more easily quiet down. Be the patient observer of your mind and know that you are not your thoughts.

I highly recommend some of Jon Kabat-Zinn’s books, and/or some of his videos on YouTube. These have been very helpful to me.

Try meditating on Conway's Game of Life ;)

On a more practical note, I just find that I make more mistakes when I'm not paying attention to what I'm doing. And as for planning for the future, how much extra time would it really take if you saved it for after the dishes? A couple minutes?

All that said, I still listen to podcasts while doing chores...

You'll do both things more efficiently if you give them your all rather than having your attention constantly flit between them. Imagine if, while programming, you had to switch between projects every five minutes. You'd never get anything done! Yet we expect our brains to perform well under the same harsh circumstances.

Of course, if you don't care about what you're doing, it doesn't really hurt to let your mind wander. You'll probably do a sloppy job, but you don't care anyway. But the real payoff to concentrating on something like washing dishes is that your mind gets better at concentrating, so you'll instinctively do it when it really matters. It's like muscle training — you don't want to wait until you need to heft a couch to start doing it.

Brain doesn't work like that. You can actually do stuff in parallel without performance penalty as long as the tasks you are doing use different types of mental resources. I find it easy to wash dishes well while simultaneously planning my future / thinking about whatever. Quite often the thinking I do while washing dishes or in the shower is much better in quality than the thinking at my desk or near the whiteboard.

Sometimes it's best to use your time to actually practice your football skills, go out on the field and play; or else spend that time planning the next game, doing strategy and stuff like that.

But other times it's best to go to the gym and lift weights. That may seem like a waste of time for a football player, but it actually makes him stronger, so he gets better results in the game - because he engaged in a seemingly unrelated activity. Strangely enough. ;)

Same with washing dishes. Sometimes you use that time to draw plans for the future, advance the theoretical side for the projects you're working on ("play actual football with your team mates in the field"). Other times it's best to use those moments to meditate ("lift weights at the gym"). Both are useful, and in fact it's best if you practice both, at different times.

one of the most difficult principles of zen to understand and follow is "no gaining mind". this is an extension of the notion that attachment is the root of all suffering.