Same here. That advice “Eat the Frog” (doing your most difficult task first thing in the morning) has never worked for me. There have been days when I just went back to sleep when I had the “frog” scheduled first thing that day.
On the other hand, a task that’s easy or inherently interesting gets me more motivated to start. And just like you said, the momentum from completing this easy task then helps me complete the more difficult ones.