Being bored is totally normal for kids and is not even a problem to be solved. Boredom activates their imagination and motivation. If they're never bored, they never have access to those things.

My kids complain about being bored sometimes and I just tell them that's a good thing and every kid gets bored. Then within an hour they're coming up with some new game to play.

As parents we have to learn what is and is not our job. It's not our job to keep kids entertained. Once you realize that life gets much easier.