I think the sprinting has really helped with expanding my lung capacity. Because I can run a lot farther now without stopping. Which is kind of shocking considering I just came to grips with the fact that I thought I was just going to be a interval runner forever. Here's a couple tricks I use that seem to help me.
1. chewing gum while running helps the dry mouth
2. turning my music way up helps drown out my breathing, so I can push myself harder.
3. setting in my mind a specific spot I want to run to and running to it, rather than watching the stop watch for an allotted about of time.
I think that's it.