Answer: Life (and you thought I was going to say merry-go-round)
Not to get too philosophical people, but it's very true that we live in a world of cycles. My husband is thrilled to see me write this, as he's been extolling this truth since 2005. One day you're down, the next day you're up...and repeat.
Case in point: Tuesday sucked. On Amazonian levels. Work was stupid complicated, I felt like my belly was being ripped in half, and I was exhausted. Today? Work was ah-mazing, my belly is cute, but I am still exhausted. You can't have everything (another truth).
I am told my Nana used to say, "this too shall pass, dear" and I have to agree with her. Bad or good, everything is temporary and runs it's cycle. I am beginning to think the key to happiness is embracing this perspective. Not that it's easy. By the time you're my age you are pre-conditioned to react in certain ways and it is no small task to teach an old dogs new tricks (NOT a truth). But it can be done.
Armed with this perspective, it's amazing how the bad becomes just a little more tolerable and the good that much better. I have been through hell and back throughout my life, and will of course repeat this in future years (see, I am not delusional)...but this time I'm prepared.
Murphy's got nothing on me.