How serious should you take a Game?

I've thought about this for awhile now.

As my group's primary GM, I put a lot of thought and effort into each game. I do it because I like it and I feel my friends deserve my best efforts.

But sometimes I think I take it too seriously and go too far, putting pressure and a sense of obligation, or expectation, on my players.

I'm trying to throttle it back but I just know we can hit it out of the park when everyone relaxes and gets into it.

I'm just not really sure how to promote that.