While I think that life ought to be enjoyed, I must admit that enjoying life seems to be a luxury for richer, more developed countries. And much of our standard of living comes at the expense of poorer people abroad... even if we don't like to think about it, our enjoyment of life often comes from making other people's lives worse, both at home and abroad...
Still, that's no reason to get sad... as long as one is cognizant of that fact, one can live life well, but be aware of how one got the things we consider necessary for our high standard of living...