When someone thinks about their career, they can break it down into four quarters - just like football. The typical pastor would finish undergraduate school when he's 22 years old and then graduate with his M.Div. three years after that - making him 25 when he begins to serve in a church. For me it was 26 years old because I remained in New Orleans for a second master's. A 40 year career is something a young pastor should strive for - this means I should retire when I'm 66.
Here are the four quarters of a 40 year career:
1st Quarter - The first 10 years are the hardest. You fumble the ball. You throw interceptions. You miss a tackle and the other team scores. You're a rookie going through growing pains. It's important that you learn from your mistakes and keep getting up when you've been knocked down.
2nd Quarter - Years 10-20 is when you begin to score. You should be past the rookie mistakes that used to plague you. People begin to take notice that you're still in the game. I'm in the second quarter.
3rd Quarter - You take the lead. Years 20-30 you can score nearly every time the quarterback throws the ball to you. This is your prime - you can read defenses and force an offense to punt. You've built trust and others want to play on your team.
4th Quarter - You begin letting the second string take some snaps. Years 30-40 are when you're 55-65 years old - you know the game will soon end and you've gained a big lead, played in the Pro Bowl, and won a championship. The fourth quarter is probably the next-to-hardest quarter because the "retirement" decision eventually has to be made. Sometimes the front office makes it for you.
Overtime - You have unfinished work. You're 65+ years old with 40+ years experience. You want to finish with a win - overtime games can be most exciting!