I believe that people should always mind what they say and what they do because people always reap what they sow.
For example, a student, who is always attentive and respectful in class, walks down the hall with his or her friends and makes a negative comment about the class and the teacher. The student, however, did not know that, that teacher was standing nearby and overheard that comment. So, a few weeks pass without that incident being brought up, but that student asks the teacher if he or she would write a recommendation letter for a job. The teacher does, but comments about the hallway incident, and the student does not get the job because of it. Therefore, that student suffered the consequences for their poor actions.
For me personally, my belief was actually formed recently. Many things over these past few months have changed in my life; some of my former beliefs were tested and thus changed. A family member has just taken a big step in her life and since that step was taken, there have been many conflicts that I have had to face and have learned much from. I have found out that my family member made some very bad decisions and is now suffering the consequences for them. After seeing how it has affected her, my family, and myself, I watch what I say and what I do, because I know that later on in life I will reap what I sow.
There are also many positive ways in which one can reap what they sow. Take Theodore Roosevelt, as an example. He fought in the Spanish American war; he had many great victories and won many medals. Then, when he ran for president he won easily because of what he did personally, and because of his many other noble qualities. Also, because of the experience he had in battle, and working with other people, he was a very successful and famous leader.
So everyday when I am with other people, or even just by myself, I watch what I say and what I do because I never know who may be watching, and how my actions could affect me later on in life.