Am I physically capable of being a CNA?

Well, I don't know that any of those things on their own would make you incapable of being a CNA. I would ask yourself some questions:
Can you stand on your feet 8-12 hours a day? Not just standing, but walking briskly most of the time.
Can you lift at least 50 pounds?
Do you have enough energy to focus and multitask, or are you too sleepy to concentrate on such things?

It is more about your energy level, stamina and ability to focus. Also if I were you, I would make sure your bipolar disorder is as controlled as it possibly can be... being a CNA is a stressful job and I know it can set off my depression sometimes.

How well can you handle stress?? Knowing that many residents will be wanting you at the same time? every place I have always work we are short handed. Plus residents can be grumpy and mean- they might try to hit you- and you can't hit back. They may yell at you and you can't respond back in anger. Okay those are the things you need to think about- I can promise you this is the most rewarding carreer you could get in- A few are grumpy but most are loving- and they so appreciate you- it's like having many grandma's and grandpa's- at the end of the day I know that I did something good for them- I was able to help them do stuff they can't do by theirselves- The hugs and kisses are the huge rewards- I am glad I pick this type of work- I love what I do- by the way I'm almost 50 yrs. old. Age doesn't matter- as long as your heart is in it.

im not sure those things would hinder you.... there is a lot of a walking and being on your feet. you and I would really really really focus on learning proper body mechanics, and raising the bed to your optimal height for your back. it took me a month to really 'click' how important raising the bed and really using my base appropriately. im 29 ...... and im learning the older i get the less forgiving my back is .. Good luck

Like the other posters here have said... I don't know that any of these things would prevent you from being able to do the job... but remember that home health is an option as a CNA and might be a better pace for you if you have doubts. Good luck with your decision.