The old chinese masters imitated or 'borrowed' the actions and behaviour of animals and insects to formulate a whole system of MA involved a form of visualisation. Because it was felt that the human body was inherently weaker, slower and less deadly than animals and insects. What if I could fight like a tiger, they asked.
So imagine or visualise you have the strenght and ferocity of a tiger; the agility of a monkey; the striking speed of a praying mantis; the quick penetrative movement of a snake; the single-mindedness of a dog; the evasive maneuver of a crane; and also in combination with the innate characteristics of the five elements -- gold, wood, water, fire & earth and you will have the mind-boggling permutations which exist in some traditional chinese systems which have may be 35 or more katas.
I don't visualise I am someone or something else. But I do visualise I am the winner in a contest. Away from MA and during my school days when I was the school's 100 & 200m sprint champion, I always visualise touching the finishing tape first.