The first pitfall is accepting gifts. As the saying goes, there's no such thing as a free lunch, because chances are the person picking up the tab is looking for a favor. This doesn't mean you need to be cynical and think everyone is selfish, but if you do get invited to lunch, it doesn't hurt to question the motives and wonder whether it isn't, say, just a ploy to get you to work overtime. In short: pay for your own lunch.
The second pitfall is not having a morning routine. Having a regular morning routine is great for reducing the amount of mental energy you use, since you don't have to make any decisions – everything can just go like clockwork. This means you'll have more mental energy to spend on more important tasks later in the day.
Third is the mistake of prioritizing busywork. Always focus on the big goals and taking the steps that get you there.
Similarly, the fourth pitfall is prioritizing easy tasks over difficult ones. Don't do it!
Pitfall number five is to be overly reliant on the eight-hour workday. Remember, you only have five hours of high-level mental energy available. So it's all about being efficient and focused during these hours while spending the rest of the time resting and recuperating.
The sixth and seventh pitfalls are the ever-present distractions of smartphones and incoming email. Constantly checking social media, texts and email wastes mental energy. Avoid these pitfalls at all costs.
The final pitfall is giving in to requests from others. Again, this is about becoming comfortable with saying that magical two-letter word: No.