I do not have one as I found the 'life-long-mission' thing is very uncertain and challenging to follow. That doesn't mean that, I do not have dreams. I have dreams, wish, ideas but nothing for a very longer stretch.
I try to keep my goals shorter as much as possible and found it has advantages:
But that's me and I am sure, many may not agree with it.
Another area I realized is important is, planning for your goals. Be it short, long or whatever size, without a plan to follow them is of no use. In fact it is waste of time in making those goals. I also believe, it is the most difficult part. How to keep you motivated and follow it regularly.
Here is what I do(again same medicine may not work for all):
Sorry for a long answer but, as you have asked a great question, I couldn't limit in few lines! Thanks for asking.