You should get yourself certified with NITROX and dive the different blends. While in California I was diving NITROX and had to make a long surface swim while breathing off the blend. I felt like I was doing great because I wasn't getting tired as in the past when I've had to make a long surface swim. Then I remembered I was breathing NITROX and boy did it make a difference. A lot of times on driving home I've continued to breathing a NITROX blend driving home.