I think without a doubt the hardest part of sleepless nights and lifting someone who weighs 72 pounds isn't being tired and having a sore back. It's the mental exhaustion from having done it for a long time and knowing that we will hopefully be doing it for decades to come.
It's no different than not wanting to suffer through the bedtime routine with your small kids one more night. It's no different than struggling with addiction for a lifetime, or having to choose to forgive something tough every day for the rest of your life. Life's circumstances often weigh heavy on our minds, but it's not usually the task at hand that is impossible. It's all the tasks from the past and the future added up that seem too heavy to bear.
Somehow that one tough diaper change when I had just changed her and put her pajamas on can be enough to undo me. That one diaper takes on the weight of every one I've ever changed.
We do all the "right" things. We have date nights, I try to exercise, Findley builds things, but it can still feel like too much.
I return to the same two prayers often. I pray that I can take life one step at a time. (or one diaper changed, one lunch packed, one story read at a time!) And I pray that I can keep a light heart, perhaps the biggest challenge of all. It's not the physical task at hand that's overwhelming. It's the repetition. So I just have to constantly think "just do the next thing" and "laugh while you're doing it." Definitely not my natural reaction, but what's the other option?