Implementation intentions are self-regulatory strategies that increase the probability that desired goals will be achieved. While their effectiveness in the short term is well established in the literature, the long-term effects are not. The present study, which was conducted in France during the COVID-19 lockdown, aimed to test whether reminders could support the effects of forming implementation intentions over time. It proposed to help people adopt a new behavior: to set themselves three daily goals for four weeks and send the results to a dedicated website. A total of 118 participants (from an initial sample of 194) sent their three daily goals at least once and constituted our final sample. A 2 (implementation intention: with vs. without), ×2 (reminders: with vs. without), and ×4 (week: 1-4) repeated measures ANOVA was conducted. The results showed significant main effects for all three factors, from small to medium to large. However, no significant interaction emerged. Hence, text message reminders did not seem to intensify the effect of forming implementation intentions.