At any given moment, you may feel as though your ability to succeed in the world involves some combination of your own efforts and factors that are out of your control. Starting about 50 years ago, psychologists began to explore the relationship between people’s beliefs about the amount of control that they have in a situation and their behavior.

This work suggests that people who believe that their efforts drive success in situations tend to work harder and to do more positive and healthy things than people who believe that factors outside their control are affecting outcomes. Essentially, when you believe that your own actions matter, then you work to create the outcomes you desire. When you believe that your actions will not have much of an impact on the future, then you do not put in much effort.

A key concept in this work is . People with an internal locus of control believe that they are the authors of their destiny. People with an external locus of control believe that circumstances control their future. Much of the work on this idea has focused on locus of control as a trait that is relatively stable over time.

An open question is whether there are variations within individuals in locus of control that also affect the way they act. This question was addressed in a paper by Holly Ryon and Marci Gleason in the January, 2014 issue of Personality and Social Psychology Bulletin.

They had a sample of pregnant couples fill out a daily survey for three weeks. The women were in their last trimester of . Their non-pregnant partner also participated. Pregnant couples were used (in part), because they are likely to experience a lot of and changes in health on a daily basis. Most people’s lives are a little less adventurous than those of pregnant couples as they approach their due date.

Each day, they filled out a number of scales. One measured locus of control (with questions like “Today I was able to deal with my problems” and “I feel that I have control over the things that happen to me.”). They also filled out measures of and . They reported whether they exercised and ate a healthy and also any negative health symptoms they experienced. They also reported the hassles they experienced that day (including health problems, car problems, financial problems, and issues with their partner).

One set of analyses demonstrated that the daily hassles people experience affect people’s perceived locus of control. The more hassles, the more that they felt that circumstances controlled their lives. The anxiety they experienced that day also affected their locus of control.

Daily differences in locus of control then predicted behavior and symptoms. For both the pregnant partner and the non-pregnant partner, the more they believed that their actions controlled the future, the more that they engaged in healthy behaviors like eating well and exercising and the fewer negative symptoms they experienced.

This work extends previous studies by demonstrating that even day-to-day changes in your beliefs about your own effectiveness in the world influence your behavior. On those days when you feel like you are in control, you act in healthier and more proactive ways than when you believe that the world is controlling you. When you feel like you have no control, it can be valuable to engage with other people and let them help to motivate you to act in healthy and productive ways.

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