I use Streaks religiously to track my habits. I recommend reading Atomic Habits and slowly building 2 minute habits, make notes and watch how these tiny changes accumulate over weeks and months. Streaks also makes it easy to ignore days, archive habits and export your data.
I can safely say it changed my life.
I use Obsidian for all my writing. Personal notes, a personal diary I keep since 2019, writing this blog and managing some personal knowledge bases on coding, cooking, fitness and more. I use different Vaults stored on iCloud. Using a symbolic link I can read the folder into the Gatsby project and easily deploy to Netlify. Already used everything out there from Evernote, to Google Keep to Notion over the years and don't think about migrating from Obsidian.
I use Hevy to track my workouts and it works nicely with the Apple Watch. Saving different routines, recording milestones, warm-up and failed sets and sharing every workout in detail is fantastic.
I use iCloud to store digitalized documents, screenshots I don't want in my gallery, old drawings, wallpapers and a lot more. It worked best for me than Google Drive or Dropbox.
I use Google Sheets for anytime I need to save data that involves dates or costs. I avoid LibreOffice and never paid for Microsoft Office.
I use Kindle for reading. Just the app, not the device since I heavily use different highlight colors the device does not support.
I use Apple Health especially to track my weight, sleep time, sun exposure, body fat and control my AirPods volume.
I use Apple Shortcuts to quickly set my iPhone to a "reading mode", quickly search my way home on Google Maps and notify me when the battery is on 20%.