Very minor in the grand scheme of things, but we bought our dog a doghouse when he was a puppy, nearly 6 years ago. We showed it to him. He went in it for all of 30 seconds then came straight out and has completely ignored it ever since.
Until last week. One day at the beginning of last week, he ventured into it and he’s barely left it since when he’s out in the garden. I’m inordinately pleased. Maybe he’s fed up of us all being home and just wants another cosy den to hide in? 
6 years. Am glad I kept it now!