Calvin Leach's goal was to lose 5-10 pounds in 2-3 weeks to improve his performance as an athlete. His plan was to track calorie intake, eat only at scheduled times, and work out 3 times per week doing activities like running, lifting, and combat sports. While he faced challenges like unhealthy foods from housemates and car problems limiting gym access, he was still able to lose 6 pounds through focusing on his diet and workout schedule.