I'm 43 and I'm retaking A&P this summer and finishing a pre-req in the fall. If I get into my school's ADN program, I'll be starting in Fall 2016, so no, 40 isn't a big deal. I took a lot of nursing pre-reqs ten years ago and most of them transferred. I feel like I'll have more to bring to the table as a student and a nurse at this age than I would have in my 20's, honestly.