I remember this story when my high school teacher relate this in our physics class. Indeed, no can skip problems in our daily life. But sometimes, we complain to God regarding our problems. Sometimes we want to know the reasons for every problem that we encounter. If God will not reveal the reason, that’s the time that we cut down the burden we carry then complain. The more we cut down our cross the farther we are to God.
But in end, we learn the best lessons in life. Learn to trust God's timing because everything happens for a reason. Along the way, God will surely unfold the reason.
If we carry heavy load, be it. Don’t grumble.