Consistent with the proposition that people need to exert autonomy over their decisions, prosocial behavior is most likely to lead to happiness when actors have chosen to provide help

Helping and Happiness: A Review and Guide for Public Policy. Lara B. Aknin  Ashley V. Whillans. Social Issues and Policy Review, August 6 2020. https://doi.org/10.1111/sipr.12069

Abstract: Perhaps one of the most reaffirming findings to emerge over the past several decades is that humans not only engage in generous behavior, they also appear to experience pleasure from doing so. Yet not all acts of helping lead to greater happiness. Here, we review the growing body of evidence showing that people engage in a wide array of prosocial behaviors (e.g., charitable giving, volunteering, blood/organ donation, offering advice, food sharing) which can promote positive emotions. Then, using self‐determination theory, a foundational theory of human motivation, we consider when and how generous actions are most likely to boost the helper's happiness—and when they are not. Finally, we leverage these insights to consider how public policy and organizations can apply this information to make prosocial action more emotionally rewarding for citizens and employees alike.