I retired at 40 so 52 is ancient by my standards. I had gone through more than enough stress. I worked out that I had more than enough to last me till my deathbed. I'm sure retired ministers are in the same situation after earning millions during their tenure.
They want to take things easy, earn a bit of pocket money and enjoy what they were deprived of when they held public office.
I can fully understand why they don't want to return to high flying corporate life or a stressful practice.