Swimming Novice

Question
Hello, I have just started swimming regularly about a week ago, and, as a novice, I have a  simple question:

Whenever I start swimming, the first two laps are relatively painless, but after that I get progressively tired and I have to take long breaks (to catch my breath) between each lap. Other people don't seem to have this problem: they go on and on and on without even taking breaks.

I have to say that I'm a very inactive person (I'm a student; I sit most of the time), and I suspect that the cause of this might be my low, undeveloped lung capacity and general physical weakness. Do you have any suggestions in regards to some strategies that can be used to counter this problem? Or is this just a matter of time?

Thanks.  

Answer
Andrew-
Don't worry about it.  Since you just started it will take a little while to build up your endurance.  As you stroke technique improves,it will also become easier to go further before breaks also.
The  people who seem to go on and on have probably been swimming for a while, give yourself some time and you should be cruising right along with them.  If you have access to a coach have them watch your stroke and see if you can get any pointers to help you improve.
Hope this helps,
George