Sargeant struggled through his rookie year with Williams, having an early tendency to overdrive a difficult to handle FW45 to keep up with team-mate Alex Albon.
While the Floridian made gains through the latter half of the year, which saw him rewarded with a second year, he still only ended the season with just one point amid what he felt was a draining experience.
Having realised he was physically behind of where he needed to be, Sargeant completely altered his preparation for 2024.
"The offseason has been such a good opportunity for me to take a step back and look at myself from mental, emotional and physical standpoint where I need to do improve, where I need to get better," Sargeant said at Williams' season launch.
"I learned that I need to manage myself much better. I let myself get very drained throughout the season and I let that affect me off the track, which ultimately brings it onto the track.
"I wasn't physically in the place I need to be and I've done everything I can to get on top of that. For example, I'm five kilos heavier than I was at the end of last year, and I feel much more healthy and much more ready to go.
"I feel like a different man, I feel like physically I am in the best shape I've ever been. And I believe in the condition I'm in now and will continue to get to will be simply just helping me feel more comfortable in the car and extract performance."
Source: Autosport