Sometime back I read a devotional about this Bible verse. At the time I was in despair. I read it at the end of a very difficult day and I hadn't coped very well. In two days time I knew it was going to be the same kind of difficult day again, and I was dreading it because I knew that once again I would not cope well. It was just too difficult and I know my limitations!
So when I read this devotional, I was very weak. And I thought 'What does this mean? Am I strong right now? No way! That verse doesn't even make sense anyway! It's a contradiction of itself! How can you be strong when you feel so weak?"
The night before the next difficult day, I was still despairing. I prayed, "It will take a miracle for me to cope well tomorrow."
The next day I was amazed because I coped perfectly. I thought of ways to make it easier and at the end of the day I was still happy.
Then I understood what that verse meant.
When I am weak, I learn to completely depend upon God. So in myself I am weak, but I am strong because God is helping me.
Then I take no credit myself because I know it definitely didn't come from me!
This song sums it up.