I am a retired public school teacher who retired after 38 years. I highly endorse lessons for the following reasons:
My daughter, Kelly, began lessons at age 11, at first in a group at a local community college. After she said she enjoyed them, I got her private lessons at a local club from the assistant professionals. (They charge a lot less than the head pro and are better with kids.) To make a long story short: Kelly lettered 4 years in high school and won her high school section title as a senior. She has been working in New York City, but because of the training she received as a youth, can still play once or twice a year when she comes home and still have a more than respectable game, hitting the ball over 250 off of the tee.
My wife began golfing only after she saw what a great time Kelly and I had together on the course. After finding an inexpensive set of clubs, I took her to the driving range. (It must be noted there was golf in her genetics, as her grandfather first shot his age at 66.) When she seems to enjoy the driving range, I got her a better set of golf clubs and encouraged her to take groups lessons with a local female instructor. Now she is a golf addict and loves playing 9 holes and going to dinner on a weekly basis. We also do a number of couples events with friends every summer. (On a funny note, when she began golfing, her goal was to make a score on any given hole with a name: bogie, par, snowman, etc. Now that is not an issue.)
I took my first and only lessons at age 26 from the Golf Digest Schools in 1976. I was single at the time and had spent one month's salary on golf clubs and another month's salary gong to the golf school. Being a teacher, I took careful notes, practiced religiously, and became a 6 handicap. I am now a "Happy 9" handicap 37 years later. When I need a refresher, I go back to my original notes, or I utilize the tips and experiences that I have gleaned over the years. I know that if or when my game would go south, I would not hesitate to seek the advice from a local pro. [One note about the Golf Digest School I attended. The instructors were Bob Toski (leading PGA money winner in 1954 and member of the World Golf Teachers Hall of Fame), John Elliott (former tour pro and noted instructor), but I spent most of my week working with Peter Kostis (CBS golf analyst).]