One easy way to get more hard stuff done is to do it in the morning.
Simply change the order in which you do things so that the really valuable work comes early.
Early in your day, your cognitive capacity is highest. You’re fresh and you’re most capable of being creative, learning new things, and staying focused.
Doing the hard stuff early does not mean doing it at 5 a.m. Cutting your sleep short is the most counterproductive thing you can do.
For example, I tend to get up between 9 a.m. and 10 a.m., so when I do something “in the morning”, that typically means between 11 a.m. and 1 p.m. The specific times don’t matter too much, as long as you’re sleeping enough.
If you need to say “no” to office meetings so you can have your morning hours back, then do that. Protect your most valuable hours of the day.