First, in the mental plane and second, in the physical plane.  A thought in a mind becomes an action done through the body.

It is very easy to see the passion(invisible) for gardening in your mind reflecting in the beautiful garden(visible)  around your house.

So, the body is only an instrument to carry out an action propelled by the impressions or thoughts in the mind.

Your dreams indicate the traces of impressions in your mind. Because mind can not project what it has not known or experienced before.

The body keeps changing; it is not the same body that went to sleep, when it wakes up in the next morning.  But the mind remains the same as the ‘all time doer’.

Bhagavatham says that your present life is a proof of how your past was and an indication of what your future is going to be.

(Bhagavatham 4.29.52 – 4.29.85)