Years ago, back when I was single, a married couple around my age said something I never forgot. They had been married a short time, maybe a year. And one of them used a quote from someone else to describe that year. I remember the quote as, "It was the most difficult and the most wonderful year I've ever been through."
I keep remembering that because life in general keeps being like that. Some periods (like our early marriage) have been more wonderful than difficult. Other aspects (like parenting) have been more difficult. But there's always been that mixture, rather inseparable, of the stuff I was thrilled to see in my life, and the challenges that I never asked for, but were firmly attached to the first category.