physical addiction is different bc you wont almost kill yourself without using the drug after a while. some poeple say take one 80mg oc. they pass out. someone whos been taking them for a while could take like 2 80's and be normal. its bc now theyve reached a point where they cant really get up without it.
I think you're mixing physical addiction with tolerance. They do relate because with some drugs the higher your tolerance the worse your physical withdrawals will be (heroin for example) but not all drugs cause life-threatening withdrawals. Heroin withdrawal may get pretty bad, but they wont kill you. Benzodiazepine withdrawls can be life threatening if the addiction got that bad.
kr1Nx01 has the right idea, virtually any activity can be psychologically addictive.
Heroins physical withdrawal symptoms include the runs, nausea and vomiting, muscle aches...these do not develop immediately after one stops using the drug but may start a day after initial use and peak on the third day before they go away.

Physical withdrawals are not easily developed and even with drugs such as Heroin take a good while of consecutive use before appearing. There are many misconceptions about the addictiveness of drugs.
In fact, a sizeable percentage of heroin users consume only occasionally, without becomming heavy users (Zinber 1979), and measuralbe withdrawal symptoms from opioids rarely occur until after serveral weeks of regular administration (Jaffee 1991: 67).
Drug War Crimes: The Consequences of Prohitibtion