Recently, there was news about new drugs that may soon replace opioid painkillers. It is said that with a potency comparable to morphine, there will be significantly fewer side effects and "is unlikely to be addictive."
It has also been shown for a long time that with prolonged running, the level of cannabinoids in the blood increases, that is, the runner's euphoria is a condition similar to that which occurs after using marijuana.
Apparently, "internal" drugs, which are produced by the human body itself, can be classified as conditionally harmless. For example, regular exercise (bodybuilding) causes the release of internal drugs. A break in training leads to a slight irritability and aggressiveness of the athlete, since the body does not receive the usual amount of dopamine.