The two biggest learnings I've had about productivity and effectiveness are centered around the two most important components we have: time and energy.
The strength and vitality required for sustained physical or mental activity.The definition of "Energy"
Most people assume the physical component of energy, but they'll often overlook the mental side of it. And that's the most important side when it comes to getting things done.
Identify your energy levels.
The first step is to identify your own energy levels. When are you most alert? When are you the most productive and effective? When are your sluggish? These are the types of questions you need to answer, and you need to be in tune with yourself to identify this.
Optimize your time around your energy.
Once you identify your energy levels — the highs and the lows — you'll be able to determine which blocks of time in your day are best-suited for specific tasks. For example, if you're most energetic during the morning, maybe that's the time to focus on more highly cognitive tasks: design work, development or coding, strategy, writing, and brainstorming. If, on the other hand, you are more sluggish after lunch (aren't we all?), then you can put some of the lower-energy tasks in that block: email, chat, administration, etc.
There's no sense wasting time on tasks when you don't have the time or energy. Focus on how you feel, identify where your energy levels are at its peaks and valleys, and then plan your day accordingly. Also, realize that not every day will be the same. Maybe you have less energy in the morning than usual because you didn't sleep well, so you need to perform different tasks.
Adapt, evolve, and focus your day.