I think if you attend more carefully, you will see that all of those lovely experiences are stained, so to speak, with a tincture of wistful sadness, since you know that they are impermanent and are passing away before your eyes. Your friends are corpses-to-be. The beauty of the flowers and shrubs are fleeting and doomed. The little insects and frogs live for only a moment as they move around furtively craving food and mates. In your own mind, your enjoyment is hindered by a disquieting sense of things left undone, or imperfections that need to be made more perfect. Everything is pulsating with a painful longing for something more, better, other.
It seems to me that this consciousness of pain is always with us, although we suppress it to some degree hen we are enjoying ourselves, and is what the Buddha described as an arrow embedded in our hearts. The Buddha’s path is about removing that arrow, bit by bit.