If there's one common quote that really gets under my skin, it's that one: "Make it fun!"
You don't have to MAKE baseball fun. It IS fun! That is why we're playing it in the first place!
I hear that quote most around youth baseball. It comes often from parents who complain that their sons are bored at practices, or that coaching is too stressed out. Well, those are valid complaints. But so often people want you to turn practices into a series of entertainment events. Kind of like when you go to an MLB game and spend your time wandering the concourses looking for the sideshow distractions.
If the kids are bored, keep practices fast paced and challenging. If the coaching is abusive, replace it. If the coaching is pushing for performance and not getting it, then evaluate whether the problem is with too much vein-bulging yelling, or maybe with too many people thinking the objective of a baseball practice or game is to replace a video game or a TV show as an entertainment venue.
Too often the "make it fun" crowd is in that last category.
What teen players especially need to learn is that there is a brand of fun more deeply satisfying than the instant gratification kind -- the kind that comes when you practice hard and practice well, and then end up getting more hits, pitching better, fielding better, or playing together as a team for a team win. This is where baseball can really help kids mature and appreciate the kinds of fun that are more deeply meaningful than any thousand instances of the momentary kind.
I really can't see any grandpa taking a young lad on his knee and saying, "Let me tell you about the time we turned baseball practice into a series of silly things," any more than I could imagine him saying, "Let me tell you about this killer video game we had when I was your age." But MY grandpa loved to tell me about his exploits in the old coal mining towns' semi pro circuit.