Interruptions are one of the most challenging aspects of working with others. Like everyone, you want to be reasonably accessible to the people you work with, and a true team player. But an over-the-top need to people-please can be a time trap; if you spend all day in helper-mode it's at the expense of completing more revenue-driven tasks.
Learn to discriminate between truly urgent matters and those which can wait, so you can minimize interruptions without becoming a bottleneck.
Buy yourself some time. We are far less efficient when dealing with an assignment reactively, than when we come in prepared. If you can defer an interruption by even a half hour, that will enable you to prepare yourself to discuss the matter in a more focused way. Just because someone brings you something in the moment, don’t assume it has to be handled instantly or is a crisis. Ask if you can come back to them
Put the new request in context. Remember that people pleasing includes more than the person standing in front of you at the moment. Before you say yes to a derailment (just because it’s hard to say no), consider whom else you promised to deliver something to that you might end up disappointing. What commitment might get short shrift if you take this on?
Alternate between “Closed Door” and “Open Door” times. Most people need to balance their time between their own focused work, and responding to members of their team. Build several “open” times in your schedule throughout the day to handle interruptions on your schedule, instead of on someone else's. One way to do this is a visual signal. Following our corporate training workshops, many teams introduce a flag or sign system that colleagues can see from afar if you are in focused or uninterruptible mode.
Empower your Team. If you're supervising people or working on a team, empower people to make decisions so you're not constantly inundated with tiny questions. If someone comes to you with a problem they could handle on their own, turn it back around: "Can you make that call? I won't be able to get to it for two days" or "Come up with a few solutions, and then let’s meet."