It may sound crazy but I’ve found that each time you hit a new “longest fast” level, it will be easier to get to that point the next time.
Example, the first 24 hour fast is the worst! Then you wait a few days and do it again and it’s not so bad, so you push it to 48 hours and that second 24 hours is the worst! Then you wait a few weeks and do it again and it’s not so bad, so you push out to 72 hours and that last 24 hours is the worst! Rinse/wash/repeat.
Fung and Ramos talk about fasting being a muscle and my experiences agree with that, the body just seems to remember when it’s “time to eat” even though you may not need to intake nutrition for survival, making fasting such a powerful thing in that it re-sets those “clocks” and helps us to form new routines.
I’ve found that keeping any IF schedule of some sort helps as well, the longer the period of IF, the easier long term fasting tends to be (for me) BUT, the shorter the eating window, the more nutrition I have to get in and that can lead to feeling too full, it’s a trade-off.
Best of luck on your future efforts.