We tend to underestimate the time it will take to complete a future task despite knowing that previous tasks have taken longer.
What you can do about it:
<ul>
<li>Break projects down into smaller parts and estimate how long each will take.</li>
<li>Add 20% to your project timeline. Finishing earlier than expected is better than being surprised by it.</li>
<li>Use historical data to make better predictions.</li>
<li>Limit the scope of the work. It means leaving off some things for a later stage.</li>
<li>When you're going to miss a deadline, communicate that early and often.</li>
</ul>

The Planning Fallacy

We are inclined to believe that complex solutions and explanations are better than simple ones. The perception of complexity often leads to avoidance.
What you can do about it:
<ul>
<li>Instead of seeking to understand a concept fully, opt for action. Try things, see how they work, then slowly improve over time.</li>
<li>Choose the system you'll stick with long-term. Look for strategies that will work with your natural ability, even if they are not the most effective.</li>
<li>Apply Occam's Razor to counterbalance the complexity bias. When faced with two possible explanations for the same evidence, the one with the fewest assumptions is likely true.</li>
</ul>

Complexity Bias

This effect describes our tendency to remember incomplete or interrupted tasks better than completed tasks. Each unfinished task takes up some of your attention, splitting your focus. It also interferes with your sleep.
What you can do about it:
<ul>
<li>Write your tasks down as soon as they come to you.</li>
<li>Have a system in place for organizing and regularly reviewing your tasks.</li>
<li>Have an end of work shutdown ritual, so your unfinished tasks don't stay in your mind after-hours.</li>
<li>Take a small step to help you get started. The act of starting can help you keep going to the end.</li>
<li>Don't forget to review your completed tasks and celebrate what you've already accomplished.</li>
</ul>

The Zeigarnik Effect

Economists used to believe that people will always choose the option that maximizes their well-being. But people act against their rational self-interest all the time.
We procrastinate and eat junk food and say yes to the things we don't have time for. Two Israeli psychologists found that we predictably make the same mental mistakes that can be avoided if we are aware of them.

We All Tend To Make The Same Mental Mistakes

We quickly return to a relatively stable level of happiness despite positive or negative external events. We pursue a promotion and believe it will make us happy. When we get it, we are temporarily happier, only to get back to our baseline levels the next week.
How to overcome it:
<ul>
<li>Set many smaller goals instead of one big one that can only give you a one-time bump in happiness.</li>
<li>Enjoy the process, not just the outcome. If you're trying to lose weight, savour the satisfaction of feeling fitter, not just hitting your ideal weight.</li>
<li>The outcome won't make you happier, but the act of showing up regularly can.</li>
<li>Pursue strong social connections. Studies find that it is the strongest predictor of long-term happiness.</li>
</ul>

Hedonic Adaptation

We want to finish what we've started because of previously invested resources, even if it is better to quit and use our limited resources elsewhere for better returns.
What you can do about it:
<ul>
<li>Every decision has two costs. The first is the actual amount of money, time, or energy, and the second is the benefit you would have gotten from the next best alternative.</li>
<li>Do a quarterly inventory of your commitments. Decide if continuing a goal or commitment is worth it.</li>
<li>Ask yourself if you were just starting this endeavour today, would you still do it?</li>
</ul>

The Sunk Cost Fallacy

We tend to choose a smaller, immediate reward over a larger reward in the future. For example, playing video games is more enjoyable than writing or coding or designing.
What you can do about it:
<ul>
<li>Help your future self. Automate your savings; lock yourself out of your social media apps and websites at certain times of the day.</li>
<li>Find ways to make the "right" thing more pleasant. Do exercise you actually enjoy; find healthy recipes that are also delicious.</li>
<li>Reframe how you think. Enjoy the process rather than only focusing on the rewards. Instead of running to lose weight, focus on the satisfaction you get after running a mile.</li>
<li>Imagine your future self to help motivate you to choose longer-term payoffs.</li>
</ul>

Present Bias

This bias addresses why we do unimportant tasks we think are time-sensitive over tasks that are not time-sensitive, even if the non-time-sensitive tasks provide greater rewards. 
How to overcome this bias:
<ul>
<li>Use the Eisenhower Matrix. It will reveal the urgent/not urgent and important/not important tasks.</li>
<li>Block off on your calendar the most productive 2-4 hours each day for your most important work.</li>
<li>Only answer emails at specific times. Don't allow email to bleed into other time.</li>
<li>Give your important tasks a deadline and find a way to commit to it.</li>
</ul>

The Mere Urgency Effect

Good news, you're not lazy! Your brain is just hardwired to sabotage your productivity. Here's what you can do about it...

Complexity Bias

Similar ideas to Complexity Bias

Why we are drawn to complexity

Closeness-Communication Bias

How to reduce the egocentric bias