Practice waiting

Remember the famous Stanford Marshmallow experiment? This was a study on delayed gratification on small children, 

where the child was offered a choice between one small but immediate reward, or two small rewards if they waited for a period of time. During this time, the researcher left the room for about 15 minutes and then returned. The reward was either a marshmallow or pretzel stick, depending on the child's preference. In the follow-up studies, children who were able to wait longer for the preferred rewards tended to have better life outcomes, educational attainment, other life measures