Have a plan for each session or else you will not be 100% productive. Do squash specific workouts such as agility work, interval training, and squats. Good drills are rotating rails, boast-lob-volley-straight, back court games, and solo hitting. Always warm up before working out or playing a match. Don’t be afraid to take a day off, but be sure to stretch to prepare for the next day(yoga, foam roller too).