Carrying a brick.
Somehow, let's say, you get to know that there's a brick in your bag as you are trekking.
You have momentum now, you know you can carry the brick. And to remove the brick, you will have to stop, get the bag down, open it, find the brick and then throw it.
What if it's not a brick? It's something that might be helpful down the line. The chances are less. But still. You can see a situation where you might want it.
What do you do? Keep carrying?
As Mohammed Ali supposedly said, it's the pebbles in our shoes that stop us more than the mountains in front of us.
The challenge is in stopping, taking off the shoes and getting the pebbles out.
In the moment, it's always easier to take the next step with the pebbles still paining.