What is boredom?
It has many definitions and aspects. It is easier to define it by its exact opposite, which comes when you are so busy you can't scratch yourself.
In retirement you may find yourself getting bored, with the absence of activity. The whirlwind of work having stopped.
Perhaps boredom is a name for the activity (non-activity) of taking the time to find out what interests you.
Beware of distraction, which comes in the form of incessant checking of mobile devices - Facebook, email, LinkedIn etc. - as it may be nothing more than a deferral. A deferral of the search for your meaning. Let the boredom take over and honour it with some time in your day, I suggest.
Retirement: you won't know what it's like until you get there.