Anyone else swimming this Summer? I've been following

File: lane_lines.jpg (72KB, 1024x676px) Image search: [Google]

72KB, 1024x676px

Anyone else swimming this Summer?

I've been following http://ruthkazez.com/swimming/ZeroTo1mile.html. I'm a decent enough swimmer from childhood but currently trying to rise above neet-tier cardiovascular fitness. On the third week right now and it's a lot of fun.

Problem is, every day when I start swimming, I feel deeply uncomfortable and panicky for the first time I go >100m. When my head is below water I feel like I'm drowning. I breath every 2nd stroke a lot like I'm exhausted even though I just started swimming . If I push through it and keep going, after a while I feel comfortable and this feeling goes away and I can swim for a long time. But the difficult beginning is a little annoying and makes the whole session less enjoyable. Are there any warm up breathing exercises I can do to stop this?

Otherwise, swimming general.