It's not nearly as full-featured as a regular fitness app, but it literally can't connect to the internet so there's no way anyone can get my health info.
Forest is a simple step counter that shows you the steps you did today, with a little extra info.
Doable is a tasks/reminders app. It's not the most feature rich, and notifications are only in beta, but I love the design and it does what I need well.
Data Monitor shows you how much data you've used in your current plan, and you can see which apps use the most data (or wifi).