“Live the Present Moment!”—Developing the 100-I-K Scale to Examine the Relationship Between Mindfulness and Stoic Attitude

Objectives This study aimed to analyze the relationship between mindfulness and Stoic attitudes by exploring their unexamined similarities. Moreover, it sought to develop a new tool for assessing Stoic attitudes with a broader scope than previous measures. Method A total of 437 individuals participated in the initial survey, and 347 were re-surveyed after 2 weeks. Participants completed the newly developed 100-I-K questionnaire and an additional scale to measure mindfulness. The follow-up sample completed the 100-I-K scale, Freiburg Mindfulness Inventory, Pathak-Wieten Stoicism Ideology Scale, and a control question. The participants were recruited through an online Computer Assisted Web Interviewing survey panel as a representative sample. Results A strong positive correlation was found between mindfulness and Stoic attitude in both the first ( r = 0.65) and second ( r = 0.63) measurements. A weak, yet statistically significant relationship was observed between 100-I-K scores and understanding of the Stoicism ideology in the first measurement ( r = 0.19) and follow-up sample ( r = 0.21). Moreover, Stoic attitude correlated with subjective declarations of adopting Stoic attitudes ( r = − 0.19 and r = − 0.18 in both samples). Conclusions The results confirmed the relationship between Stoic attitudes and mindfulness, suggesting similarities between Eastern and Western traditions. The 100-I-K questionnaire needs further development; however, it demonstrated the potential to assess the overall Stoic attitude. The relationship between mindfulness and Stoic attitudes remains stable over time. Preregistration This study is not preregistered.