How do you not get fatigued with recording things?

I'm actually a bit surprised that I was able to maintain my recording for over a year. Some reasons why I think I was successful in hindsight:

1. Since I made the tracking app myself, I was excited to use it for the first little bit.
2. I intentionally made my tracking app such that I could see my daily, weekly, and category totals, all at once for a given week, which is important for me since my primarily unit of productivity measurement/planning is the week.
3. I came to realize that tracking all of the categories was key to the whole thing working. By tracking e.g. miscellaneous stuff (which seems pretty pointless at times), you're given a constant reminder that you are "covering all your bases."
4. After tracking pomodoros for several months, not tracking pomodoros made it feel like I wasn't being productive.
5. Once I passed a critical threshold, I was motivated by the thought of having an entire year's worth of data.

What are your recommendations for amount of structure before you incorporate pomodoros? Is there any structural/organizational stuff you should have set up before you do them?

You need basically zero structure to start using pomodoros; just a task and some time to work on it. (I say this especially because I'm really bad for wanting my system to be "perfect" before I use it.) I treaded the pomodoro waters for several months before delving in to tracking everything. My organization system, in short, is having a +/-5 year plan, a current year plan, and current quarter plan, and current month plan, and then specific tasks/projects for the current week (which I roughly estimate in pomodoros, or at least aim to hit a certain total for the week).