Each of us only have so many days and none of us know what number that is. Any time there's a scarce resource, using it wisely is great advice. So it makes sense to take stock of what you've accomplished, what you're working on now, and what you plan for the future. Make your time count.
It's fair to say that some days are better than others. The goal is to make the number of good ones outweigh the marginal ones by a wide margin. For that to be the case, you need to begin each day with an idea of what that good day looks like; you should end it by determining if you hit the mark.
A good day can be vastly different things to different people. Don't worry about them, however, because you can't control their ideas or their outcomes. Focus on yourself when it comes to what constitutes a productive use of time. What do you care about? What pursuits give you personal satisfaction? What things do you do that enrich the lives of others? What good things accomplished today will make tomorrow even better?
It's one thing to get up and go to work. It's entirely another when you start out with the purpose of making it a good day and then set about the activities that will make it so. Having a good day is mostly a choice. Make yours accordingly and have a Good Day!