Any action which depends
strongly on mathematical or spatial skill, or minute details, can
potentially serve as a good reality check. The following list is
composed of those that I have used successfully in the past. These
are effective because of their strong differences from regular
reality.
Write a favorite
proverb, joke, or other phrase on a standard-sized note card. Keep
the note card in your pocket. Throughout the day, refer to the note
card at random intervals. This is a strong reality check because,
unlike checking your watch, this has no other purpose than to
establish whether or not you are dreaming.
Look down at your shoes.
Close your eyes, think of another pair of shoes that you own, and
look again. In a dream, you are about as likely as not to find
yourself wearing the other shoes. A standard means of changing what
is happening, once you are in a dream and lucid, is to look away from
the scene and look back. Anything your attention is not focused on is
subject to change.
Try to fly. In the
waking world, it is, of course, impossible - and I don't mean that
you should flap your arms on the street corner to give yourself a
reality check. In a dream, you will be able to fly, sci-fi spaceman
style, by looking up, stretching your arms skyward, and blasting off.
You may imagine that you have jets on your shoes or back. In polite
company, this can be disguised as a stretch - it will still work if
you are, in fact, dreaming.