DO NOT TAKE HARMFUL DRUGS
People who take drugs do not always see the real world in front of them. They are not really there. On a highway, in casual contact, in a home, they can be very dangerous to you. People mistakenly believe they "feel better" or "act better" or are "only happy" when on drugs. This is just another delusion. Sooner or later the drugs will destroy them physically. Discourage people from taking drugs. When they are doing so, encourage them to seek help in getting off of them.
DO NOT TAKE ALCOHOL TO EXCESS
People who take alcohol are not alert. It impairs their ability to react even when it seems to them they are more alert because of it. Alcohol has some medicinal value. It can be grossly overestimated. Don't let anyone who has been drinking drive you in a car or fly you in a plane. Drinking can take lives in more ways than one. A little liquor goes a long way; don't let too much of it wind up in unhappiness or death. Deter people from excessive drinking.
Observing the points above,
one becomes more physically able to enjoy life.