Q: I'm a pretty shy and quiet person, and as such prefer to deal with people at work via e-mail or instant messaging. My boss is pushing me to call people or stop by their desks instead. Do you think he is being reasonable?
A: Take your boss' advice and broaden your communications skills; it'll serve you well short and long term.
The inner game
Technological tools for communicating are valuable, but need to be used for the right purposes and in concert with more personal methods. Take some time to think more deeply about your communications preferences. Do you find the same pattern in your personal life?
What feelings come up when you're dealing with people more directly? For example, you may be concerned about being put on the spot and falling short (at least in your own mind). To counter this, think about times when you've had enjoyable and productive conversations and consider what made those work for you. Now, take some deep breaths and let the negative feelings you might experience arise, and release them with your breath. Teach yourself to recognize them and not let them control your behavior.
Think about other people's points of view. If you avoid direct communication, you may seem unfriendly or uninterested. Not only does this take a great deal of potential joy out of the day, it can also seriously impede progress on work matters.
Also recognize that personal style plays a part in these preferences, and learn to build skills where you need to. For example, if you're an introvert, you may need more time to think through questions rather than thinking on the fly. If that's the case, spend extra time planning before phoning someone with a question.
The outer game
If you haven't done so, ask your boss about this topic. It may be causing performance issues, or could just be that he's interested in supporting your development. It's worth being clear on his motivations.
In terms of behavior, start practicing the new approach. Start on something easy — if you have a quick question for your co-worker, instead of messaging, walk over and ask (it's good to get up from your desk anyway) or pick up the phone. Set goals for yourself so that you're interacting directly more and more each day. And when you reach these goals, make sure that you have a reward waiting.