In reality, all people can do is manage their commitments. Regardless of what people think and do, time does go on.
Do you agree?
If you accept the first claim, then you can notice observe and assess that we make endless tradeoffs for one value or 
concern over all the others in the given moment. For example, many of us at the office are competing in a Biggest Loser competition. In order to be competitive I must work out on a regular basis. When I’m invited to go do something else during my time to work out I must decide if the tradeoff is worth it in the moment. What’s more important to me given the circumstances?
All humans can do is think and act. So we can tradeoff thinking about a concern, rather than acting to take care of that concern.
Once you begin to have fundamental principles, ethics and morals when it comes to keeping your commitments, sorting out all of the tradeoffs you must make becomes simple. This is because you will be able to anticipate what direction your choices will likely lead over the long run.
Are you constantly in crisis mode regarding managing your time? Did you ever consider that you may just need to say “no thank you” when a request conflicts with a higher concern that you are already committed to? Do I go to lunch with a friend or do I go to lunch with a potential customer? Who do I say no to? In my case, I am committed to growing Jenco so I would have to say “no thank you” to my friend and go out with the potential customer. Do I go to the gym or do I go to the hockey game I just got invited to? Since I am truly committed to shedding the extra pounds I’m carrying around, I know that I need to pass on the game this time and get into the gym. The examples are endless.
It’s ok to pass on opportunities when they conflict with your priorities. If you don’t get good at saying “no thank you” you run the risk of other people’s priorities taking precedence over your own. You also will become overwhelmed and will end up missing out on being able to say “yes” to the things that are important and could help you take care of your concerns.
If you truly think of every commitment as trading off one thing for another you will be able to make better assessments of the opportunities that are thrown your way, manage your time better and ultimately become less stressed.