I realized that my mental resistance to the anaerobic pieces, feeling a measure of dread for each one before it started, was causing a time warp between my ears of which even Stephen Hawking would have been proud.
I remembered my purpose for doing the course and resolved to let go of the fear of the pain, but rather to embrace it as supportive of my current stance on my health and fitness. For the last few sets, having let go of the fear I found I was able to slow down my breathing and engage fully with each pedal stroke. Instead of hating the pain in my legs, I found that if I actively focussed on it, the pain dissipated. For the last three anaerobic pieces, my recorded wattage (a measure of power) increased, despite my tiredness.
Lessons learnt: Firstly, letting go of fear allows you to focus on what is real and gives you more power. Secondly, bringing your mind to bear on physical discomfort, moment by moment, has you connect with yourself in a way that allows the pain to be part of your precious self, rather than an enemy to be feared. Whether your pain is physical or emotional, totally embracing and immersing yourself in it somehow helps to still the pain.