If you truly want to go to nursing school
and become a nurse, you can do this.
Like you, I was 53-years-old when I started nursing school, following a 15-year career in another profession. When I graduated from my ADN program, I was 55, and had NO problem finding a job. A year out of nursing school, I am now on job number three, as I am still trying to find my niche within nursing.
The physical aspects of the job probably do catch up to folks in their fifties (for those who started in their twenties), but if you have previously had a sit-down job, like I did, and you are in good shape, you will be fine.
I have no problem with 12-hour shifts. And I work 7p to 7a. In fact, after work this morning, I drove an hour to an appointment and was told I didn't look like a person coming off of a 12-hour overnight shift. The remark was: You don't look haggard.
Believe me, I was tired!
So, if you want to do this: Do it. You only have one life to live, so make it count.