Im not sure there is advice to give here, but someday I hope to remember to do stuff before my legs start burning rather than after.
My legs will start to burn and then I remember to relax them, pedal through, use both legs equally, and breath.
The funny thing is, I relax and remember to pedal circles and the burning stops as I actually start going faster.
I'll be happy when I don't have to think about it so much.
It's getting better though. 30 days ago I rode 10 miles at 12mph and was dead. Today I rode 16 miles at 15 mph and was able to power up that last hill of the ride without crying.