Thoughts are mental cognitions—our ideas, opinions, and beliefs about ourselves and the world around us. They include the perspectives we bring to any situation or experience, which color our point of view (for better, worse, or neutral). An example of a long-lived thought is an attitude, which develops as thoughts are repeated over and over and reinforced. While thoughts are shaped by life experiences, genetics, and education, they are generally under conscious control. In other words, if you are aware of your thoughts and attitudes, you can choose to change them.
It may be useful to think of emotions as the flow and experience of feelings. These can include (but are not limited to) joy, sadness, anger, or fear and can be triggered by something external (from seeing a friend suffer to watching a movie) or something internal (an upsetting memory). While emotions are universal, each person may experience them and respond to them in a different way. Some people may struggle with understanding what emotion they are experiencing.
Emotions serve to connect us with others and help cultivate strong social bonds . This may be the evolutionary purpose of emotions—people who were able to form strong bonds and emotional ties become a part of a community  and were more likely to find the support and protection necessary for survival. Researchers such as Nicholas Christakis and James Fowler, authors of Connected, have also found that emotions are “contagious.” We have a tendency to mimic each other’s outward states (for example, by smiling when someone smiles at us), and our outward states can affect our internal ones (smiling can actually make you feel happy!).
Emotions can also be influenced by other factors:
Thoughts and emotions have a profound effect on one another. Thoughts can trigger emotions (worrying about an upcoming job interview may cause fear) and also serve as an appraisal of that emotion (“this isn’t a realistic fear”). In addition, how we attend to and appraise our lives has an effect on how we feel. For example, a person with a fear of dogs is likely hyperattentive of the dog across the street and appraises the approach of the dog as threatening, which leads to emotional distress. Another person who appraises the dog’s approach as friendly will have a very different emotional response to the same situation.
According to Christakis and Fowler, “People the world over have different ideas, beliefs, and opinions—different thoughts—but they have very similar, if not identical, feelings.”
We tend to believe that emotions are just “part of us” and can’t be changed. Research, however, has established that emotions are malleable. They can be changed by altering an external situation (divorcing an abusive spouse), shifting our attention (choosing to focus on a more positive aspect of a situation), and by re-appraising a situation (the upcoming test is an opportunity for learning, not an assessment of my personal worth).
How we choose to live our lives has tremendous power over the way we feel every day. Certain types of mental training, such as meditation or positive thinking, can affect our perceptions of the world and make us feel calmer, more resilient, and happier. Other researchers have identified many other helpful attitudes—such as forgiveness, gratitude, and kindness—that can be cultivated with practice.