Sending your little one off with the expectation of having fun every day puts everyone under so much pressure, the child cannot help but fail and by failing will often feel as though they are disappointing the parent who so clearly wants them to have fun.
What can we do instead?
Surely there are many meaningful ways to measure the worth of our experiences?
Using instead the phrase "have a good day" is very different to "have fun. A good day can be (and very often is) one where you achieve something worthwhile, you master a new skill, you persevere and make progress, you overcome a difficulty - it may not have been fun but it was satisfying and rewarding.
When our children return home at the end of the day we could say something like, "Hi, it's great to see you, how are you?" and leave it to them to report their day as they wish (often you will find out much more by waiting than you will by grilling them).
"How was your day?" is far more open-ended than "how was your day, did you have fun?" which automatically tells the child what the parent wants to hear.
If you ask, 'how was your day?' please be prepared to accept, OK, all right, boring, horrible or good or any other words the child chooses to describe their day.
Very often if you accept the child's answer, reflect it back and wait, children will begin to spontaneously talk about their experiences in their own way, in their own time. If no additional information is offered up it's a great idea if you offer some of your own, talking about your day. This then becomes a conversation rather than an interrogation.
Conversations, where we are free to discuss our experiences and our feelings, are the basis of a great relationship.