Here are some of the primary influences of moods and emotions. Moods and emotions have a personality trait component, meaning that some people have built-in tendencies to experience certain moods and emotions more frequently than others do. Affectively intense people experience both positive and negative emotions more deeply: When they’re sad, they’re really sad, and when they’re happy, they’re really happy.

Moods vary by the time of day. However, research suggests most of us follow the same pattern. Levels of positive affect tend to peak in the late morning (10 a.m. to noon) and then remain at that level until early evening (around 7 p.m.). Are people in their best moods on the weekends? In most cultures, they are—for example, U.S. adults tend to experience their highest positive affect on Friday, Saturday, and Sunday, and their lowest on Monday.

Many people believe that their mood is tied to the weather. However, a large and detailed body of evidence suggests weather has little effect on mood, at least for most people. As you might imagine, stressful events at work negatively affect moods. A review of nearly 100 studies on 25,000 employees suggests that the effects of chronic stress also build over time. For most people, social activities increase a positive mood and have little effect on a negative mood. Sleep quality affects moods and decision making, and increased fatigue puts workers at risk of disease, injury, and depression.

You often hear that people should exercise to improve their mood. Research consistently shows that exercise enhances peoples’ positive moods. While not terribly strong overall, the effects are strongest for those who are depressed.