Hi @JGreengrass!
Overall, this session should be challenging but should not be nearly impossible to finish. Training isn’t always about hitting your maximum - in fact, only on occasion should a session put you at your limit…and this one generally should never put you there. It might be good to make sure that your current FTP and MAP settings are accurate…as generally speaking, most folks will see heart rate getting into Zone 4 by around the 5th or 6th effort during these kinds of sets/efforts. Keep up the great work!