Mathematics seems to be hard

I have been trying to do mathematics again with a collaborator after a long gap. It takes long to understand even the stuff one used to know and longer to sort out simple mistakes. After a few days with a lot of help from Peter, I got into thinking mathematics. But it was difficult to put those things on paper and when I tried they kept changing. Finally after a month, I have been able to write six pages which may help. The ability to keep a problem in front and thinking about a problem for days which I acquired late in life still seems to be there and strangely it seems to make me feel physically better. At the moment I can walk longer and work more than before in the garden if there is enough time. What is surprising is that it takes so long to get some thing sensible. If it is like this in mathematics (for me) I wonder how much I goof outside mathematics. One guess is that many ideas and words are not precise in one's thinking and there is a sort of band width to them. In a subject like mathematics, there are mechanisms of proof which helps sorting things out and fitting them together. It is not so clear cut in many other areas.