Tips and or exercises to improve eye focus?

[Logan]

So long story short, I have been having a lot of headaches and I went into the eye dr and he told me my vision is great and my eyes are healthy. The only thing that wasnt good was my focus. He told me he would give me a C- on the grade scale and this could be a big factor in my headaches, my eyes struggling to focus. If anyone could help give me some tips and exercises to do that would be awesome. I got some reading glasses last night for when on the computer or reading so thats step one. I really want to improve my actual focus too though so any input would be greatly appreciated. Thanks