God says it in His Word, and He's a faithful God who keeps His promises. I can say with confidence that His grace truly is sufficient. Everything in me was screaming, 'I can't', but He reminded me to keep leaning on Him, to keep holding on to His promises - His power is made perfect in our weakness. His grace IS sufficient!! What an awesome God!!
2 Corinthians 12:9 - But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.”