From deep breathing to angry naps, we've tried pretty much every quick stress-relief tip out there. But according to new research, one of the easiest ways to feel better about all the stress in your life has been hiding in plain sight: You just have to be polite.For the study , published online earlier this month in Clinical Psychological Science, researchers used data from 77 people who were originally recruited for another study about drinking habits. Participants were asked to keep track of their stress, mental health, and moods using a survey on their smartphones once per day for two weeks.As part of that survey, participants were also asked about how often they performed "prosocial behaviors" each day. These included little things like holding the door open for someone else or asking others if they needed any help.Unsurprisingly, participants who reported feeling more stressed out also reported having more negative emotions and worse mental health. But on days when those stress-ridden participants performed more prosocial behaviors, their moods weren't as negative and they tended to rate their mental health as being more positive compared to days when they weren't as helpful. People who were exceptionally helpful of others didn't have any significant drop in mood level — even on days when they reported feeling a lot of stress.Previous research has shown a pretty strong connection between the amount of time we spend helping others and all kinds of healthy benefits. Doing things for other people has been associated with lower blood pressure, increased self-esteem, and even having a longer life . But, as the authors of this study write, "[These] results suggest that even brief periods of supporting or helping others might help to mitigate the negative emotional effects of daily stress."So, while it would certainly be appreciated, you don't have to venture too far into the world of charity to feel the benefits of being a nice person. In fact, you don't really need to go out of your way at all: Basic politeness seems to be enough. Hopefully we can at least manage that.