To counteract climate change people should adopt lifestyles consisting of numerous pro-environmental actions, across different domains, sustained over long time periods. Thus, it is important to understand how initial pro-environmental behaviors can impact the likelihood of subsequent behaviors. We tested the hypothesis that people use mental bookkeeping of past behaviors, allowing them to limit pro-environmental behaviors after having performed similar ones, and investigated the role of affect in this context. Participants read campaign messages framed affectively neutral (Experiment 1) or positive/negative (Experiment 2), followed by fictitious scenarios in which they could perform a second pro-environmental behavior after having shown a first one. Participants indicated a smaller willingness to act pro-environmentally if the behaviors were similar. Positive affect increased the likelihood of showing subsequent behaviors and mitigated negative spillover driven by behavioral similarity. However, the observed effect sizes are too small to be of practical relevance for developing efficient intervention strategies.