The way I was taught was to think of the tai chi form as a moving meditation, so during the form I focus on slowing down my breath which in turn clears my head whilst calming and slowing me down, as well as improving awareness of every part of my body.
I've been practising Yang style tai chi (mostly Chen Man-Ch'ing's Short Form) on and off for four or so years now so let me know if you're keen for a/some tai chi lesson/s!