If you asked people what is the biggest challenge they face in this life, I think most would point to family strife, a hated boss, financial stresses, or a major health crisis like cancer.
But Galatians 5 says humanity's biggest problem is NOT external.
Our biggest problem is IN-ternal.
Our flesh and our spirit are opposed to each other.
"For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do." (Gal 5:17)
But the flesh isn't some equally matched "big dog", doing battle with the Spirit, as the famous sermon illustration would have it.
When Jesus was in the garden praying in anticipation of his betrayal and death, the disciples could not keep themselves awake to pray with him. And in that moment, He told them, "The spirit is willing, but the flesh is weak."
He didn't say, "The flesh is strong. It will overpower you."
No. He said it's weak.
It's a sandbag. An anchor. It suffers from inertia. It would rather sit on the couch, watching TV and eating Cheetos. It can't be bothered.
It takes the path of least resistance. It is largely passive, only aroused by what is easy, pleasurable, or fun. If it encounters a bit of friction, it shuts down regarding anything that isn't feeding its own appetites.
The flesh is NOT the all-powerful, unconquerable force we imagine it to be.
It is not ferocious.
The "flesh" is a couch potato.