There are some things which we can't separate from our personal lives. Some people say "I mix business with pleasure" while others claim that "it's not personal", whether it's related to business, faith, or whatsayyou. Now I'm not here to debate whether you can indeed mix business with pleasure, or whether you should take everything personally (or not, depending on how you see things). But I do believe that your faith is integral to your life, whether you're Christian, a Buddhist, or whatever your religion may be.
I'd like to clear that I'm a Christian so I'll take it from the perspective of my faith. I think one thing I notice is that many Christians suffer from "Sunday Christianity", or acting religious only on Sundays (or whenever you go to mass). Since I grew up in a Catholic school, I also see other extensions of this, such as me and my classmates behaving right after a recollection or retreat, but no longer than the immediate duration (which ranges from several hours to a few days). First of all, I don't think any religion asks you to be "part-time" in your faith. It's a 24-hour, 7 days a week ritual. Sure, there are specific times when you're required to worship (such as Sunday mass) but faith is not about those particular times. Faith isn't just about duties; it's about living your life in a particular kind of way. It's like saying you're vegetarian when you only eat vegetables once a week and eat meat the rest of the week. To be a real vegetarian, it has to be part of your regiment, an integral factor in your daily existence. The same goes for your religion. You don't really get to choose your time to be a practitioner of your faith; as long as you live and breathe, you're devoted to your faith (even if your belief is, say, atheism, the same principle applies).
Perhaps another good reason why your life and faith can't be really separated is the fact that your personality determines your faith. Let's face it, our personality shapes our religious preference and those who are truly zealous in their faith sometimes alters their personality to suit their religion. In the bigger picture, we chose a particular religion because we think it's the best one for us. And to a certain extent, the reason why we want to spread our faith is because people in general want to share a good thing. For example, if your friend was living an unhealthy lifestyle, wouldn't you want him or her to eat good and healthy food? The same goes for our faith; we offer something which we think is good. Of course in the end, it's up to the person to either accept it or reject it. I personally don't think religion is something we can force on other people, but we can provide them with the necessary information to make an educated judgment call and perhaps nudge them in the right direction (people seldom change for the sake of doing so; it usually requires another motivation, such as a guy practicing good grooming habits because he's meeting his crush or behaving in front of a teacher who you're infatuated with).
Many students complain that they don't get to practice what they learned in school. But strangely enough, when it comes to faith, I see many people doing the opposite. I mean it's in real life that we get to apply our belief, the tenets of our religion. Yet when the opportunity arises, many of us shy away from such circumstances. We become "undercover" practitioners. My advice to you is that there's no such thing. I live in a Catholic-dominant country and perhaps the biggest problem with that is that one assumes everyone else is a Christian even though not everyone acts like one. In a crowded bus or street, I really can't identify if the other person is a Chrisian or not. If, on the other hand, there was a devout Muslim (probably because of their attire) or perhaps a Buddhist (buddha beads and shaved heads fad aside), I'm sure I can identify them in a crowd of undercover Christians. I think what's essential here is to stand out and perhaps the only way to do that is to practice what you preach. I don't mean preaching literally, by the way, but it can be seen in your behavior, in the way you talk, in the way you act towards other people. And perhaps in a country that's dominantly Christian, that's difficult to do so because we take Christianity for granted, something that has reached the status of mundanity. Missionaries smuggling Bibles into China probably get more excitement and adrenaline rushes, but it's no less important than living out a life of piety in a country where your religion is already prevalent.
I personally follow the rule of multiple agendas. I mean when I meet a person, I intend to be their friend. But along with intending to be their friend, I also want them to share in my faith if that's possible. That doesn't mean I get preachy to people the first time I meet them but given the right opportunity, I'd probably take the time to share my faith (which is also why I have this essay in the first place). When we meet people, faith has to be a priority, but it's not necessarily a priority we act on immediately. And sometimes, we also have to learn to let go. As I said before, we can only provide the opportunity, but it's up to the other person whether to accept it or not. Intruding on their right of choice might jeopardize the friendship, for example, and friendship is a top priority of mine as well.
Rather than seeing faith as a separate part of living, I see it as an essential element, just as our personality or emotions are part of who we are. Many people have a misconception that they can separate it from who they are but what's actually happening is that they're not really being true to their religion, or to who they are for that matter.