First, imagine that anything is possible. There are no limitations. List where you will live and what you will do.
Then, think about your impact, revise the list so that it reflects the impact you wish to have.
Next, consider the unknown factor--your death. Cull the list again, prioritizing the items from that which the means the most to you to those things you can live without. (you may want to omit this step for those under 40)
Finally, begin the process of achieving your dreams!
Where will you live?
What will you do?
What objects will you have?
Who will you spend time with?