Yes, to a degree you will need to have "suck-it-up" mindset.
You have to have a lot of self-control and backbone.
I became an aide at 18 and I remember the first time I had to "keep it together". I was in a hot steamy stuffy shower room when a resident decided that would be the perfect time to defecate (Oh! Do you know how often that happens? Answer: A lot!). Anyway, it was very unpleasant, but I had a very vivid thought (so much so, that I remember it today). I thought, "Welp, this is what I signed up for. I won't show it bothers me."
That's exactly what I did and continue to do.
Unpleasant experiences are part of nursing, so there's no crying over it. You just carry on and get it done (and you want to get it done without embarrassing or making your residents/patients uncomfortable-- it's about them, not us).
Somebody has to do this job and if not us, then who?
Even on days where something sad or frustrating is going on, we chose to do it and we just remind ourselves to keep it together. It's a lot of mental self-encouragement.
The nursing home is often where new CNAs get their feet wet so those hospital jobs are easier to get, but I cannot stress that even if you are in it just for the experience, you have to give your 100% because those elderly folks need you.
I cannot think of any other jobs that hoists so much responsibility on a teenager-- and bless all of them who do it and do it well.
I'm not sure where you are, but I can only guess by your username.
In that case, I have noticed most psych hospitals around here utilize PCTs in their geriatric units (though they may work on other non-geriatric units on occasion).
I am a Geri-Psych nurse who worked my unit as a PCT for several years before I became an RN.
On my unit, in my hospital (which I can only speak for) we want PCTs who have experience working with geriatrics, especially dementias. This typically means that we want nursing home experience.
If you worry how you will react in a nursing home, I must tell you that you have to really really get your emotions and reactions down pat because it is a HUGE aspect of psych. Not everyone can do it (but if you can, it is a very cool job for a CNA-- I loved it!).
How you learn to "suck it up" (I hate that term, but it's true) is totally up to you, but a positive attitude, realistic outlook and giving the best care you can will go a long way to help.
Cheers and good luck!