I went on at 55, but I sort of cheated. I was home with my kids for 20 odd years and did not have to work. So I could be sick and it didn't affect working. (But it did affect my kids.) So I worked a total of 15 years. I too, was goal oriented and was a school principal at age 25. Bipolar and mania took all of that away from me. I am glad to be on ssdi. No way could I work. I embarrassed myself so often at work and I don't have to go through that anymore.