I may have mentioned these before, but I think I will again. Start out in your 53/11 from a dead stop, and pedal as hard as you can for one minute. It will peak in about 10-15 seconds, and then slowly grind down. I don't look at the clock until I count the cadence to 40 in my head, which makes it slightly more bearable. Rest/easy 2-4 minutes, then repeat. Do it 6 times. Then do the same, but only 30 seconds, 6 times, with 1-2 minutes rest. Then 15 seconds, 6 times, 1 minute rest. Make sure resistance is set so cadence doesn't go above 90.
You'll thank me later.