Everyday helping is associated with enhanced mood but greater stress when it is more effortful.

Our affective states can influence whether we help others and after helping we often experience improved affect. One important factor determining whether we help, is the amount of effort involved. Using an ecological momentary assessment approach across two measurement bursts (N = 803; N = 303), we investigated the affective antecedents and consequences of everyday helping in terms of participants' self-reported momentary stress and mood valence, with a specific focus on the perceived amount of effort involved. Regardless of the amount of effort involved in helping, participants reported more positive mood valence after helping across both measurement bursts. In burst 2, this mood boosting effect of helping was strongest in those reporting lower mood prior to helping. In burst 1, we found a bidirectional relationship between stress and helping effort: the greater the effort involved in helping, the greater the perceived stress both before and after helping. Contrary to our preregistered hypotheses, changes in stress or mood valence did not precede helping regardless of the amount of effort involved. Our results support previous work linking helping to enhanced mood but suggest that when helping is more effortful it is both preceded and followed by greater stress. These findings have important implications for fostering and sustaining prosocial behaviours, especially when effort is involved.