John 12:37-40 quotes Isaiah 53:1 pointing out how the scripture of Isaiah is played out. What blinds our eyes and hardens our hearts? Disobedience.
Obedience is a matter of will, not emotions, or reason. In the Message translation, Jesus says they “wouldn’t so they couldn’t”.

“Wouldn’t” addresses our choices and will. “Couldn’t” address our ability. The will comes first. The choice comes first. Someone who is not able to quit smoking needs to check out his true desire or will. Someone who cannot stick to a diet for health reasons, needs to ask himself “Do I really want to.”
In my own experience, if I chose not to do my homework, then no matter how hard I tried, I could not do it. If I do choose not to be on time, then I would always be late.

Isaiah says, “They chose not to hear and repent or I would have healed them.”

What are you choosing today? Are you choosing to do things God’s way? If you are, you could do what’s required, and He will be there to see you through.

For two years now I am a Crossfit exerciser. Four years ago, the Lord told me I needed to engage in serious exercise to stay fit for the work in His kingdom. I first started at the local gym just doing things my way at my own pace. I noticed I was not improving in strength, endurance, or mobility. So then chose to join Crossfit, where there is a coach encouraging me. I chose to let a coach push me to do things I didn’t think I could do.  I am now stronger, more fit than ever doing exercises I thought were only for gymnasts. I don’t always feel like going to exercise, but I choose to and that has made all the difference to me.