How long did it take..

It took me at least a year of swimming a lot.

The trick that worked for me was to swim a lap as slow as possible.  This helped my overall comfort in the water and assured my brain that even if I got tired, I would not drown as I could always rely on this ridiculously easy effort.

When a swimmer is out of breath after 25 or 50 yards, it's not because they are not fit enough.  70 year olds (even those with horrible swim form) can swim 500 yards straight just fine.  The reason you're out of breath is because you are not comfortable in the water, and your brain is sending uneccessary signals to your body to avoid drowning.

A video of your swim would help the folks here give you some specific pointers but I think Jason is right...you're going too fast. 

I started doing this about 15 months ago (I'm 54 now) and I was gassed after swimming 75 yards.  I took some lessons to re-learn a proper swim stroke, bought some fins (to work on my kick and improve ankle flexibility) and a pull buoy (to work on my catch/pull).  I worked on the drills/workouts the instructor gave me (ie. kick sets, catch-up drill, bi-lateral breathing, etc...) for a couple of months before joining her masters class.  Roughly 1 year after starting, I swam 6100 meters as part of a end of year set in December...with a little perseverance, I know you can do the same.  If you want quick access to some drills to work on you can go here...  http://exceltriathletes.blogspot.com/ .

I remember getting frustrated too.  Be patient and don't worry about speed right now.   Focus on proper technique...speed and your ability to handle more distance will come by working on the fundamentals. 

I had been an age group swimmer when I was young, but hadn't done any serious swimming for 30 years when I started doing triathlons. 

It took me about two years to get comfortable with triathlon swimming, both with the longer distances and the  open water aspect.

Learning not to go out too fast was a big factor for me.

Good luck,

Mark

Just keep working at it. Being comfortable in the water is paramount.

Float on your back, doggy paddle, just to prove to yourself that you don’t have to “swim” to not drown.

Technique will make you more efficient and go faster but if you must believe you are safe in the water.

I spent many hours and laps in the pool and working with an OWS group before I ever raced. Started racing at 50 and love it. You can do it; you just need to get the right mindset and help to make yourself better.

As for time I started in December '12 and had a GREAT HIM Swim in Sept '13.

I'm not some awesome athlete; I'm normal as far as I can tell (maybe not all normal but...) not fast either but I was comfortable in the water and confident. I think that was more important to my swim success than my technique.

I have been at this since 2007.  I have a slow swim....but it "looks" pretty according to others so what the heck?  THer has to be some technique things I could do to improve but whatever....it is my weak link no matter what.

It took me THREE years to go from near dead last to exactly middle of the pack. And I worked fairly hard during those three years, with focused technique, decent volume/time for a beginner, and even enough hard efforts once i got the basics down. 

Swimming absolutely doesn't come to me naturally, not one bit. I feel like I've earned every second with sweat and blood! And contrary to what some of the fish experience here, it also goes very quickly for me - if I'm out of the pool for 3 weeks, I lose almost all my swim ability. (It comes back fairly quickly though.)

Swim well?  Probably 6 months the year I was 16.  I'd done BSA Lifeguard a few years earlier and signed up for Red Cross Advanced Lifesaving, Advanced Swimming, and then Water Safety Instructor and got a job lifeguarding and teaching lessons that summer.  I made a conscious effort to learn front crawl well enough to demonstrate/teach it to kids.  That included breathing either left or right. 

I swam 50 miles that summer and could swim 1800 yards in about 33 minutes (1:50/100 pace).  I lifeguarded a few more summers in college and got marginally faster.  When I did my first tri and started swimming again in 2005, I could do a similar pace and wasn't worried about the swim. 

I swam consistently in 2006-2011 and worked my pace down to 1:35/100 on my own.  The tri-club sponsored coached swimming lessons and 10 Saturdays of that and I was cruising through 100's at 1:29.  I probably swam 600,000 yards in 2006-2011 and was almost always between 1:40-1:55/100.  The 10 weeks (35,000 yards) with a swim coach watching me got me faster than the previous 5 years.  Unfortunately, I didn't swim much at all in 2012-2013.