I too am a DM candidate ( will finish up this weekend) and so far the worst for me has been the stamina parts.
The 800 yard swim with mask fins and snorkel was tough and I had to do the tired diver tow in the deep end of a pool and it was tough to make all the turns and meet the time.
I had little trouble with the book work and testing. I studied hard and was ready for the tests.
I don't use the wheel in every day diving so I had to study that to be ready for the exams.
There are no major obstacles to overcome, just some hurdles to jump over.
Good Luck.
The 800 yard swim with mask fins and snorkel was tough and I had to do the tired diver tow in the deep end of a pool and it was tough to make all the turns and meet the time.
I had little trouble with the book work and testing. I studied hard and was ready for the tests.
I don't use the wheel in every day diving so I had to study that to be ready for the exams.
There are no major obstacles to overcome, just some hurdles to jump over.
Good Luck.