From the scriptures in Galatians 5:
And from science:
The fruit of a plant is it's final outcome. It is the ultimate result of its work, and its means to reproduce. Here, Paul tells us what the ultimate outcome of the Spirit in our lives will be. The teachings of Christ are prudent and beneficial, even if they don't really lineup with our motivations. Paul is aware that it's not easy for us to be loving toward everyone. He knows that we don't feel joyful when times are tough and that we aren't naturally kind towards people we don't like. Likewise, I'm sure Paul knew what it was like to be fickle instead of faithful and harsh instead of gentle. Oh, and self-control: we don't have it.
Study the brain and you'll see that we are wired toward the immediate payout. This turns out to be a great survival strategy in most environments. We don't really have any mental hardware that will gratify thinking about the immediate with a long term perspective. Even when the consequences are dire to our health, relationships and even our society our brains want pleasure now.
To follow Jesus is to take him as our leader–to be his disciple. That process must include the disciplines that rewire our neural makeup to think on a very long timescale indeed: Eternity.
May we who believe in Christ build a lot of red buttons.