Start by giving each area of your life its own category. Then set weekly time targets so every area gets its share, and keep an eye on whether you're hitting them. Prefer a calendar? Block out time for each area instead.
What can help
Categories
Start here. Give each area of your life its own category (work, health, family, side project) so Marvin can tell them apart. Everything below builds on this. Categories are always available, there's nothing to turn on.
Weekly Time Targets
Set a weekly time target for each area, say 5 hours on your side business, and Marvin tracks how you're doing against it. Balance becomes something you can see, not guess.
Read more about Weekly Time Targets
Time Blocking
Block recurring time in your week for each area (family, health, side project) so none of them quietly gets squeezed out by the others.
Ideas to try
One category per area. Give each area of your life its own main category, like Work, Health, Family and Home.
Set your targets. With Time Tracking on, add a weekly target for each area in Weekly Time Targets, for example 3 hours of exercise. Your progress shows at the top of your day.
Forgot to track?. Weekly Time Targets can count a task's duration estimate when you didn't track time on it, so you still get a picture.
Block it in. If you live by your calendar, use Time Blocking to give each area its own time each week.
How to turn on a feature
Open the main menu and click Features, or press S.
Search for the feature by name and turn it on.
Choose where you want to reach it in the Access dialog that opens.
You don't have to try everything at once. Pick the one that sounds most like you, use it for a few days, and see how it feels.