Objectives The purpose of this study was to develop a grit improvement program and verify its effectiveness to help prospective counselors increase their mental strength to flexibly respond to various stresses they may experience in the process of building their capabilities as counselors. Methods The grit improvement program was developed according to the ADDIE model development procedure and its validity was confirmed by two relevant experts. The grit improvement program was operated for a total of 6 sessions (12 sessions), each time lasting 2 hours (100 minutes). A grit measurement tool was used to confirm the direct effectiveness of the program, and a resilience measurement tool was used to confirm the indirect effectiveness. The Mann-Whitney U test was performed to verify the homogeneity of the experimental group and the control group. The Wilcoxen Matched Pairs Signed-Rank test was performed to compare the pre- and post-score changes of the experimental group and the control group. For comparison between groups, the Wilcoxen Matched Pairs Signed-Rank test was performed. Analysis was performed using the Mann-Whitney U test. Results As a result of analyzing the effectiveness of the grit improvement program for prospective counselors, the post-average for both grit and resilience increased statistically significantly compared to the pre-average. Through this, it can be seen that the grit improvement program has a positive effect on the grit and resilience of prospective counselors. Conclusions The grit strengthening program will help prospective counselors control the various stresses they may experience during the difficult training process and reach their goal of becoming a professional counselor. Furthermore, it will help them achieve their goal without giving in to bigger challenges in life. It will help you have the strength to do it.