What have you accomplished? Do you feel good about it? Would you want to double those actions in the next 30 minutes?
The less time I have to spend on my own hobbies each day, the more I want to make the most of every minute that I spend on some task.
I don't want to waste anybody's time, and that includes my own. If I am wasting time (no matter who's it is), I am not doing a good job of time management.
Tips for having a more productive 30 minutes that I have learned from having to complete both personal and professional problems between raising kids and teaching students:
* Be prepared to start a task. If you aren't prepared (i.e. you don't know what you will be doing for the next 30 minutes) take 5 minutes to think about a basic plan of action. By having a plan (even if you end up adjusting it) you will be more productive in the next 30 minutes.
* Focus on what you are doing in the "moment." Yes, there are other tasks you're going to have to do, but don't think about them unless they are directly related to the task at hand. If I have not done anything constructive or useful in the last 40 minutes, I am not managing my time well and need to adjust what I am doing to execute more effectively.
* Be OK with making adjustments. Even though you need to focus as I said, sometimes unavoidable situations arise. To efficiently handle time-management, it is necessary to quickly improvise when challenges occur, do what needs to be done, and delegate responsibility and swing back to the critical project at hand. Focus on the problem that suddenly arose, and then return to the project you were working on so that you do not waste any time!