According to ESPN, when James was having back problems in 2015, he reached out to David Alexander, a trainer he worked with in Miami. Alexander pointed James to Donnie Raimon, a former Navy SEAL and an expert in biomechanics.
Raimon helped James work on his core strength, eventually fixing his back problems. James eventually hired Raimon full time and Raimon moved to Akron to be close to James.