Laws should not restrict us from doing things, unless other people are impacted. People should be allowed the maximum freedom; a government should never play the role of parent. If it's bad for you, it's your problem.

In those cases where society really wants to stop some behavior because it is expense or unpopular, they need only restrict half of the transaction. For instance, it might be illegal to sell weed, but there shouldn't be a law restricting someone from smoking it.

People shouldn't be forced to wear a helmet on a bicycle, but parents can be held responsible for making sure their children do (since it effects their child, who is not able to make their own rational choice). Easy eh?