Studies have also been careful to note that feeling over-taxed by the needs of others has conversely negative effects on health and happiness. For example, one study on volunteerism found that feeling overwhelmed by others' demands had an even stronger negative effect on mental health than helping had a positive one (although positive effects were still significant). Additionally, while generous acts make people feel good about themselves, it is also important for people to appreciate the kindness they receive from others. Studies suggest that gratitude goes hand-in-hand with kindness and is also very important for our well-being. A study on the relationship happiness to various character strengths showed that "a conscious focus on gratitude led to reductions in negative affect and increases in optimistic appraisals, positive affect, offering emotional support, sleep quality, and well-being".