I see many living things around me - kittens, birds, squirrels, lizards, dogs - who happily go on living their lives without bothering with such things as the bleakness of the universe or its impermanence or its meaninglessness. I then remind myself that I must appear just as wonderful a creature as a kitten, bird, squirrel or lizard to some alien observer. I would find it absurd if the three playful kittens in my house suddenly developed an existential crisis. They are kittens! Their purpose is to be happy. But the same principle holds for me too.
In other words, the problem of meaninglessness of life is a problem we create by fiat. It's a remarkable fact that we're fragments of this grand, ancient universe that have become sentient. That itself is enough of a reason to be thrilled at our existence and everything around us, including the good and the bad!