I am 55 years old and I have started, stopped, and restarted this journey called learning guitar. I found a motivational sign of the internet. It was a picture of a guy leaning over an electric guitar . Not the best posture in the world. But the message of the picture said "Practice- the less you do of it, the more you suck." Reverse psychology maybe but it's worked for me. This is a journey that you, we and I have begun. It had a beginning (or beginnings) but there is no time limit except for that which you create. If got a pulse and you are breathing you can practice guitar.