I had to think long and hard about the last seven years to find any particular sector of flight training that was easy.
The only two things that were easy for me was learning the latest avionics like GPS, and flying a glider.
Learning to land was tough, stalls more so. Learning to see without vision, the instrument rating was hard. Getting the maximum performance in chandelles and such for the commercial required extra time. The CFI I was ready for, except for the landing part. The CFII required I forget all the hard ways I was doing things and get back to instrument proficiency. The multi, well, no engines is far easier than two. Even getting the flight school's morning coffee right took a few lessons.
My definition of easy is having the right answer or doing the process correctly the first time, or definitely by the third attempt. I've heard that the desire for perfection has a lot to do with my feelings of flight training being hard.
Now I enjoy teasing two instrument pilots about how hard their training was versus mine. Both pilot seem to think they have a patent on struggling to learn skills:
"What do you mean you had a hard time with your instrument?

"You mean you didn't solo at 3 hours?"

"HOW many instructors did you go through?"

"You made a 727 go around while you were trying to land on a 10,000 foot runway?!!!"

"You BUSTED a checkride????!!!!!"
It did take six years and one year of active instructing before I could laugh at my primary flight training. . . Flying does allow humans to explore the full range of emotion.
Fly SAFE!
Jedi Nein