Mesillas Yesharim 8 (Chapter 1)

The נשמה doesn't enjoy this world, the נשמה's place is עולם הבא, the world of truth. Man is given a נשמה to refine it and thereby receive a reward in the World to Come. One can't reach עולם הבא without going through עולם הזה first. Thus the נשמה's purpose is to help us maximize our time in עולם הזה.

How do we maximize our time in this world? Through mitzvot (which are a means, not an end in themselves).

Provided courtesy of rabbisilber.com