The worst thing you can do first thing in the morning

Wow, no mistakes! :D

Really good writing! Only tiny things. So here's some more detailed help on talking about habits. There are a few natural ways to say this:

A) to pick up [a]/[the] habit of doing something
B) to get into the habit of doing something
C) to develop a habit of doing something

Note they generally use 'of + [ing]', e.g.

1. "I have picked up a habit of eating cold pizza for breakfast"
2. "I have picked up the habit of reading Lang-8 while I have lunch"
3. "I have got into the habit of doing the washing up straight after eating"
4. "I have got into the habit of keeping an eye on how much I spend on takeaway coffee"
5. "I have developed a habit of looking at my watch during long meetings"

Some slight differences:

* B) is maybe the most intentional and/or virtuous, and may be deliberately part of a regular routine. E.g. a habit which will be good for you, which you have planned to get into (as in #3 and #4)
* C) may imply that the habit was developed unintentionally, so it may be a bad habit (as in #5)
* A) could be either. Not that you can use 'a' or 'the'. 'the' may imply that the habit is more familiar to the reader (as in #2), whereas 'a' may imply a more unique habit (as in #1).

By the way, only #2 is true in my case ;)