Drawdown.  What is it? It is technically the amount of money you lose before you start drawing a profit from your Buy-in.

First.  When does it occur? It can be in the very beginning of your session or can equally be at the ending, when you are on your last few wagers before exhausting your Buy-in. (Remember buy-ins need to always be a slight percentage of your bank-roll)

Second.  IMO it should be calculated and viewed with only the amount in front of you. Not collectively from prior sessions or any kind of running tallies/totals etc.

Third.  Again, IMO the drawdown must not be viewed and compared to previous drawdowns. The presentments are different and there is no reason to compare, it will only give you false senses of confidence or worse, make you scared bettor. You have to remember, drawdowns fluctuate and will always fluctuate, no rhyme no reason to define and learn how drawdowns may appear or not. They are a fact of gambling and you need to accept  that and deal with it.

Fourth.  Emotions, pressure and other feelings will be triggered within yourself that cannot be avoided during drawdowns. The larger the drawdown the greater and more intense those inner feelings will be. So be aware and try to curtail emotions, pressure and negatively. Be ultra conscious of that, stop getting sucked in.

Fifth.  Don't confuse drawdown with stop-loss. Many fail to see the difference, but there really is. Drawdown is an undetermined, unplanned amount of money that will be lost before you realize a profit that is within your horizon of "winning the session and it is time for me to stop", thought and belief.  Just remember, you must be comfortable with some or most of and occasionally, ALL of your buy in being lost and classified as a necessary 'expense'  that goes right along with gambling. 

A little extra.  Just remember, it might not always be smooth sailing, no losses and repetitive winning. Just be ready for the worst with the proper frame of mind, proper buy in and knowledge of employing a proper money management method that actually works in your favor.

You can make it as painless and non-destructive as possible.

* Believe winners do lose
* Be smart
* Be totally conscious without getting sucked in as almost all do
* Stay in reality
* Realize what the game is
* Understand the highest majority of times a drawdown will take place,
       perhaps more than once

And, how and when you win is for the most part up to you. Likewise, how and when you lose, is for the most part, also up to you.