I was going to bring up the same idea, fitness. Be aware and careful!
I was exactly where you are one year ago. I grew up playing and had a solid foundation but had not played for 25 years or so. When I first joined the adult rec team at my local club I was amazed at the number of injuries my teammates complained about. Little did I know I would fall victim to most of the "over-use" injuries by the end of the season and was pretty beat up. (I am 45). So this year I trained like a banshee all winter and am now in MUCH better shape and am playing much higher level game and really looking forward to the season. Tennis was the inspiration, so I hope you enjoy your comeback too!