The last couple of times I've been swimming I've found that I keep a steady breathing pace and heartbeat. It requires effort, but I'm not gasping for breath which is nice. When leaving the gym I've even felt the urge to run to my car or do a lap around the block (I haven't yet, but think that I might build in the treadmill after my swims).
I went on the treadmill at my new gym for the first time and ran 1 mile to time myself on the new equipment. I increased my incline and I ran 1.5 minute intervals with a 1.5 minute walk instead of 1 minute run and 2 minute walk. It was definitely easier to do as most times I was close to the 1.5 minute mark before my lungs gave out, whereas previously I was counting down the seconds when I was only 30 seconds in. I plan to keep this up and see if I can reach my 1 mile run without walking goal before I hit my cruise vacation. That way I can run around the ship in the morning instead of walk the track. It will get me done my workout faster and leave more time for exploring and less time sweating.