If you're doing things that you’re not comfortable with just to be liked, then you're not really fitting in. Fitting in is about making your personality a part of your working environment, not letting it disappear under a culture of which you can't be a part.
If the culture of your workplace doesn't appeal to you, then it's worth trying to develop alternatives. If, for example, your colleagues often go out drinking after work and pubs are not your thing, try suggesting alternatives – an outing to watch some sport, perhaps, or a gig or a movie. The odds are that you'll soon find like-minded people who would welcome the chance to do something different.
Of course, it is possible that, despite your efforts, the culture is simply one you could never fit into. But most workplaces contain a remarkable variety of people, and trying to make connections is nearly always well worth the effort.