This study aimed to analyze the effects of a 12-week personalized full-body resistance training program, conducted twice weekly, on body composition and balance ability in 134 young adults aged 20-34 years. Participants were selected through the Korean Ministry of Health and Welfare's youth physical health promotion program in Dea-gu and underwent a one-on-one tailored exercise intervention at National K University. The program was designed based on participants’ physical characteristics and fitness levels. The intervention consisted of warm-up, main exercise, and cool-down phases, lasting a total of 55 minutes per session. Warm-ups included cycling or treadmill exercises, while the main exercise comprised progressive full-body strength training targeting both upper and lower body muscles. Cool-downs were performed using foam rollers for myofascial release. The results were as follows. First, in terms of body composition, males showed a significant decrease in body fat mass (p<.05) and a significant increase in muscle mass (p<.05), although changes in body weight were not statistically significant (p>.05). In females, significant decreases were observed in body fat percentage and BMI (p<.05), along with a significant increase in muscle mass (p<.05). Second, balance ability significantly improved in both males and females after the intervention (p<.001). This study demonstrates that a personalized full-body resistance training program effectively improves body composition and balance ability in young adults. These findings can serve as foundational data for health promotion and the enhancement of physical performance.