[2][3] He and his younger brother, Jordan, began playing tennis at age four, and his experience with the sport helped his footwork.

Justin competed at a higher level in eighth grade, after his father's friend encouraged him to play in a league in Plainfield.

[5] As a basketball player at Plainfield High School, Sears finished with historical numbers of 1,048 points and 1,063 rebounds.

[3] In his sophomore season, Sears helped Plainfield make a postseason run, and in turn, drew the attention of colleges.

[4] As a senior, Sears averaged 13.4 points, 12.0 rebounds and 3.2 blocks, and he garnered first team all-state, all-area and all-county accolades.

During his time with Plainfield, he led his team to two New Jersey State Interscholastic Athletic Association (NJSIAA) Group III titles.

He also appeared in the NJSIAA Tournament of Champions championship game two times, losing to St. Anthony High School on both occasions.