For those who are retired do you ever find yourself wanting to re-enter the workforce due to sheer boredom?

No! I do not find retirement "boring" because I ensure I fill it with the interests and activities - and their social lives - that attract me.

I understand and accept that some people will become, if not already, unable to do that, though illness, poverty or caring demands, but otherwise there is no excuse for retirement being boring.

If you can take up that translation works, congratulations. If not, damn' well find something else that interests you rather than making blanket, meaningless statements like "retirement is boring". If your own life is "boring" it is by your own choice.