Have had any non-profit board experience? Have you served on a board for a school organization? Volunteered your time for a religious institution? I mean if you have a desire to go into the NGO world, you should have some affiliation to those types of orgs somehow. You should make a list, try to figure out how you contributed, what you learned, what challenges you faced. Another important point here would be to identify any leadership roles you might have had, or if you attended leadership trainings?
The thing I worry about here would be if you have absolutely no contacts with the non profit world whatsoever. Because to say thats where you want to end up eventually, but you want to be a consultant seems to come off as a red-flag.
Look, if you can indicate your involvement with non-profits and your leadership it would be an easy stretch to say you want to head in that "long term goal" direction. However, if you don't have any experience in non profit then maybe its best not to include that in your long term goal, but rather indicate that by getting an MBA you would bring value to a non profit (ideally one you volunteer a few hours with a week?) To me, if you came in just trying to say you are interested in non profits but have no non profit experience or clue, then I wouldn't want you on the board of a non-profit unless you were planning on donating wads of cash.
Maybe you do have more exposure to non profit environment, but havent shared it here. I don't even know what you do right now for employment, so the question is very vague. If you need more help, please do share more, which might help in getting a meatier response. (And I sat on a few non-profit boards, started a non-profit, and worked at a non-profit, so i can speak from that experience.)