| Instead of developing a "runner's" mentality of working through the burn, just try playing lighter. Like WAY lighter. A few things will happen.
1. Your tone will improve. Because there is less attack, and therefore less initial decay(when the attack spike drops), your tone is fat all the way through.
2. You can drop your strings way down. Like REALLY down. So much so that the only way to have them not clack like crazy is to play light. (and other guys playing your bass will sound like hacks. Good for your self esteem too)
3. Once the string are down, and you play light, you can play for virtually days.
4. Now that you're relaxed, it will be easier to play fast. And since you haven't spent all of you energy playing the verses, you can use some for fills going into the chorus.
5. Actually, to amend #4 you'll want to relax MORE when you play the fills.
6. You now have room in your dynamic range to go WAY up. Start light, stay there for a while, and you can dig in when it calls for it. Plus there's still room to go down too.
I did the runner thing for a long time, and all it got me were sore forearm muscles. Once I relaxed, speed came naturally. Once I played light, I could respond better to a song's natural ebb & flow. | 
