There are so many distractions, all the time. Especially if you work on a computer. So many notifications, chat messages, tweets… so easy to open a new tab to check Facebook/Tumblr just for a little bit ;)
Sometimes it’s good to consciously set aside 15-30 minutes to focus on just one specific task (assignment, item on your to-do list…) and try not to let anything else distract you during that time slot. It might be hard, but it’s definitely worth it.