The knowledge that we have a choice makes that choice possible.
Circumstance defines and shapes the life of every person. Since circumstance thrusts us into the world, we can claim with some justice to be subject to its force. Each of us came into life, at the place and time that defined the initial conditions of that life, without being asked our preference. In that sense, are we not victims of circumstance, and innocent victims at that?
At the end of life, are we not equally victims of circumstance? After lives spent in the shadow of the notion of free will, we face the possibility that we will have as little conscious influence over the end of life as we did over its start.