Recent studies have demonstrated the benefits of short-term cardiac interoceptive training on interoceptive abilities and emotional well-being. However, there remains a gap in the understanding of long-term training effects. In this study, we introduced an accessible interoceptive training software, EasyIntero, and conducted a 3-month-long interoceptive training with 12 participants. On average, each participant completed 14 days of Heartbeat Discrimination training. Before and after the training, all participants completed the Trait Anxiety and State Anxiety questionnaires to assess anxiety levels. During the training, participants' heart rate variability and heart rate were automatically recorded, and participants reported their confidence levels in their judgments. Data analysis revealed that participants' interoceptive abilities improved as the training days increased. However, no significant evidence was found to suggest improvement in anxiety levels. Furthermore, we found a marginally significant negative correlation between cardiac interoceptive accuracy and heart rate and a significant positive correlation with confidence. This study explores the feasibility and preliminary findings of long-term cardiac interoceptive training. Future research should focus on setting up control groups and analyzing the multi-dimensional emotional impact.