First things first..........lessons.
Lessons are great, and I highly recommend them for people who are new to the game, but if you've been playing long enough to groove a swing and still play a decent game, be careful that your professional just makes small suggestions to help and does not try to remake your entire swing.
I started playing when I was 12 and by my mid twenties could reliably break 90 unless I had a bad day. I played my best round ever (shot an 83 on a par 72) one day and decided it was time to take lessons as that would surely help me break 80 and get into a single digit handicap.
I asked around and went to the guy who was reputed to be the best teaching pro in the city where I lived. Several PGA touring pros came to him for lessons every year during the week a PGA tour tournament was held there.
He took one look at my (home grown) swing and started to change everything including my stance, grip, backswing, etc. I had bought a set of twelve lessons from him and by the time I was finished, I was never able to break 90 again, let alone 80!
After struggling to get my game back for a couple of years, I gave it up for over a decade. Starting over again in my late thirties, I was able to get to bogey golf (around an 18 handicap) again with lots of play and practice, but never got back to the level of play I was able to achieve before I ever took lessons.