You can't simply nut-peddle and play your cards. If everyone simply played the cards they were dealt, everyone would break even since the cards distribute evenly (actually youd lose to the rake if you want to be a nit about it).

You need to set up plays, attack pots, abuse position, put your opponent on a hand and play your hand so that you can extract the maximum from him. There are plenty of times where you won't get paid off simply because they arent completely braindead or they don't have anything worth paying you off. Fortunately, the majority of 50nl players ARE completely braindead. NL is a game of situations, and you wait for the not-so-common situation where you stack someone (in comparison to when you fold pf, raise a pot, etc). You stack someone by both of you catching a hand, but on top of that, getting your opponent to put his stack in the middle. There is a huge amount of skill involved there, as many times skill determines whether you win a 20$ pot or a 120$ pot at this limit. Up until that point you should be preparing every aspect of the situation to be conducive to you stacking them.

No one said it would be easy! Sorry for rambling its late.