How It Affects Your Mood When scientists want to study stress, they often ask people to perform several tasks at once."Generally, when people go for a walk, they feel better afterwards, and this is what we saw in the phone-free walking group," said Elizabeth Broadbent, one of the authors of the study and a professor of health psychology at the University of Auckland in New Zealand.One experiment found that the more people used a phone while walking on a treadmill, the more their levels of cortisol, the so-called stress hormone, tended to rise.