Lockdowns during the COVID-19 pandemic have put people in stressful situations. Recent research showed elevated levels of anxiety and depression during this period, but no study has so far evaluated to what extent emotions and regulation difficulties were perceived by people as having changed with the lockdown. This was the major aim of the present study, together with investigating whether the emotion regulation strategy of "Refocus on planning" could be an effective strategy in this context. With a 1 time-point online survey, 635 French-, Italian-, and English-speaking participants (57.6% males, mean age of 48.48 years, SD = 15.7) evaluated (a) emotion changes, (b) anxiety, depression, and difficulties in emotion regulation, and (c) use of planning. Participants retrospectively indicated their state when thinking about the period of the Spring 2020 COVID-19 lockdown, as well as their state when thinking about the period just before. Results show that the lockdown period was associated with a perceived increase in negative and positive feelings, as well as a perceived increase in anxiety, depression, and regulation difficulties. Despite people used less planning during the lockdown, absolute and heightened use of planning was associated with more positive emotions, as well as less negative emotions, depression symptoms and difficulties in emotion regulation, whereas anxiety symptoms were lower only when more planning was adopted. This study suggests that planning is an effective emotion regulation strategy. More importantly, planning works as soon as implemented, suggesting it is never too late to start planning to alleviate emotion-related symptoms and difficulties.