It's a matter of choice. Choose to be content with people, situation and things no matter how they occur in your life, by design or default. Once your choice is made to be content, you're going to behave, act and do contenting things. This includes things that might have been viewed as discontenting in the past. The results of those actions reinforce your contentment, since you will be surrounded with contenting people, situations and things.
True choice is totally internal.
Choose to be content with both what you cause in life and don't cause of life. Take on the role of a person who sees all occurrences as an opportunity to find contentment. Play the role authentically. Respond and react to all situations with contentment. If you think this whole thing sounds phony, try this next time you don't like something.