The most important thing in life is obviously, your health. Taking care of ourselves is vital if we plan on being prepared. It will add a lot of stress to a survival/disaster situation if you are in poor health. Just having access to your meds can become a major problem. Knowing more than a little about first aid and medical skills in general is paramount to a good preparedness program. Fortunately I have several very good books on 1st aid and more in depth medical topics in my library and on data disks. Just having them isn't enough. Studying them and practicing the skills is very important if you need to remember something during stressful times.
My health isn't as good as I want. I have high blood pressure (well under control with meds) and diabetes (also under control). I have been on a diet and have been loosing weight. Cancer was a problem but its almost gone and looking very good. I recently had a bad time with my diabetes, but some good doctors took care of it and now I'm heading back on track. If you take the pills for diabetes, the pancreas can "get tired" and just quit reacting with the meds the way its supposed to. That can be a big problem, but with proper medical care, it's a short term problem. Make sure you pay strict attention to your diet!
As far as preps, I have made it a point to have 90 days worth of all my prescriptions on hand and in a safe place. By safe, I mean an area of the house that I can easily access if I have to get out. Things that concern me most are earthquakes with the resulting fires, structural damage, looting, etc. In my personal kit I keep a weeks worth of meds. I should be able to get to the main supply in that time provided it wasn't burnt up.
I wear glass's. I have at least half a dozen pairs for reading. The cheap ones from the dollar store work great for this. Just make sure to try them out. Read something with small print to see if they are the proper magnification. As far as my distance vision, it's not too bad. But, I still need correction and I kept my last pair of glass's as a back up.
One of the most important health issues during a survival/disaster situation is mental health. Having a positive attitude can make the difference between life and death. Knowing and practicing survival skills and primitive skills can give you a level of self confidence that will keep you going when everyone around you has given up.