On average, I probably spend 20 hours preparing for a typical sermon. Last year I preached 32 times. My plan, if the Lord wills, is to do that for the flock of Joy Community Fellowship for around 25 more years, if they'll have me.
That totals 16,000 hours of my time devoted to preparing to preach God's Word. That's a lot of hours. This blog post from Trevin Wax provided some rich encouragement to me that all those hours are a worthwhile investment of time.