Why am I awful at Blitz?

I don't play Blitz, it seems "wrong" to me. Chess should be about thinking. :- )

But I'm trying to get better and I'm reading Heisman and he, and Ramirez, recommend playing some Blitz games. Why?  It exposes you early to time pressure. That makes sense, you don't want your first clock panic to be a  30 or 60 minute tournament game.

So I've played some games.  All 5|0 games, I've won 5 and lost 15. And two of those wins are from abandonment early on. So it really is 3 and 13.

I often run out of time. How can I learn to think so fast? I'm guessing one answer is that I just have to play more and get used to it.

I appreciate any advice. Thanks!

This is what I tell my students around your level:

Time trouble in a classical game is very different to a blitz game. 
In a blitz game you are exposed to an entire game and have a couple of seconds per move.
In a classical game when you reach the time trouble phase you have spent time thinking about very similar positions, if not about the very same position that appears on the board.

Now to your question "How to think fast"

First learn to do the chess thinking in the right manner and only later go into going faster.
What you cannot do with enough time, you will surely do even worse with less time.

Do not stress and focus on quality instead of quantity.

Thanks. That makes a lot of sense. My local club does 5, 15 and 60 minute games. I'll just play the 5 minute ones for kicks and stay on my current journey.

I definitely enjoy longer games, at least 30 minutes. My brain is too slow for speed chess!

If you need some help with the training of longer formats let me know. Over the course of the last 12 years I have helped dozens of players as a coach.

This is exactly what I was going to post. I really need to know how to get better at blitz. I am 2100 at rapid but I struggle to maintain a rating of 1600 at blitz. Can anyone please tell me what I'm doing wrong?

At your level, you are still learning basic chess principles. It would be better to concentrate on learning those. After they become automatic in your play, you can then try playing fast time controls. But I do not recommend playing bullet or blitz until you are at least 1700. 

Does playing many blitz games teach you something? If course. But you will learn much faster and with less frustration if you spent time with books that cover the basics. A few weeks with classic instruction books is probably more helpful than six months of blitz games against others at your level.

Thanks all! Blitz is, or I should now saw, was, part of my study plan. I'm following the advice in this blog post.

https://www.chess.com/article/view/nm-robert-ramirezs-beginner-study-guide-600-1000-elo

I'm studying about 30-60 minutes per day, still playing my daily games with friends and resuming my "slow" games, 15 or even 30 minutes, need to play more of those.

Ramirez is also advocating for the Pirc and KID. I play the KID myself and get worried when new students tell me that they play such openings.

He does! He makes a strong case for them. Are you worried because they are too complex?

in the beginning players should focus on openings that are more classical. You should first learn to control the centre with pawns.

Thanks. I'll accept that.

To argue though, Ramirez point out that his two courses, which of course he is selling, let you not worry about openings at this stage in your development. At this point it is about tactics and not blundering.

I try to avoid blitz, it makes me play intuitively (not analytically) and I am not good enough to do this well.

Puzzles are a lot better use of your time, as practising these will enable you to spot a blunder if your opponent makes one.

I'm terrible at blitz too

Very good