There is a saying, garbage in, garbage out. So in that sense, what we take in, whether by what we listen to, watch or read can have a profound affect on our mental well being. If you mean mentally healthy as far as memory or learning the key is to keep our mind active.

Mentally unhealthy people suffer from some combination of poor physical health, false beliefs about themselves and others, and poor relationships. Those with physically-based illnesses such as schizophrenia have real illnesses that require medication and other biologically-based treatments. But those with less severe problems rooted in dysfunctional families or painful childhoods can improve their mental health with the following techniques: - Practice a contemplative spiritual discipline such as meditation. Most Americans are Christians, so I'd recommend Christian-based contemplative disciplines such as Centering Prayer. The goal of contemplative practice is to get some distance between ones-self and one's emotional reactions, so that one can observe them in an objective way. When one does this, one sees that one's emotional habits aren't necessarily in tune with the way life really is. A psychiatrist named Jeffrey Schwartz wrote an excellent book called "Return to Innocence" that talks about contemplative disciplines and the importance of objective observation of oneself. I believe the book has been re-issued with a less New-Agey sounding title, but you should be able to find it in the public library. If you're a smart person with the ability to think about religious matters in depth, I'd recommend a book from the Eastern Orthodox spiritual tradition called "The Philokalia," which is a collection of writings from early Christian monks who struggled with overcoming their emotional reactions by lives devoted to prayer in the desert. - In line with I just wrote, you should learn to challenge your negative thoughts. When you think that you're ugly or hopeless, stop and label the thought for what it is, the lingering emotional hurt from a bad experience, and note to yourself that it's nothing but a shadow from a past that no longer exists. Turn your attention to something else. Deprive the thought of meaningfulness. In time you'll come to see that this thought is something that you may have once thought as a child, and that this false-belief about yourself is just the mis-perception of an immature, unwise child that's somehow managed to echo in your brain. You'll see that these thoughts are boring, and that they aren't rooted in your life as it is now. - Don't compare yourself to people on TV. Realize what the average person really is - a somewhat overweight, 5'9" man with a 100-IQ who makes $36,000 a year. Many people with low self-esteem who are smart enough to contemplate it are people who are much more gifted in many areas than this "average" person. - Those who are depressed and unhappy often feed themselves with dark-themed music and movies. Don't do this. Feed your mind with positive things. At the same time, though, don't be a Polyanna. Mortality and suffering are part of life. Don't accept "positive thinking" as it's taught by so many self-help gurus or TV preachers, where you're due financial success and freedom from failure. See life as it really is. - Accept your past for what it is. If you lacked the love of a mother or if you were ridiculed by your peers because you stuttered, you aren't going to go back in time and have a happy childhood. Such things are just part of the past. Accept these things, accept yourself. Don't try to push away the experiences you wish you didn't have, but accept them and move on. - When you've come to deal with your emotional baggage, begin to move outward to relate to others with compassion. Don't worry about their acceptance or rejection. Determine to relate to other people with kindness.

Consider that your feelings are only feelings. They are not you. Consider that you may be able to let go of them. They are just suppressed, bound up energy that was meant to flow through, not into you. Consider that releasing is the first and most important step on the path to abundant mental health.