Like reconciling bank accounts, logging every last detail when dealing with fitness always seems to me to be an exercise (pun intended) in data logging frustration and subject to the law of diminishing returns. In other words, you'll spend so much time logging what you're doing that the fun will go out of the original activity. Maybe there's enough genuine information here to offset any drudgery - you can judge for yourself, since True Fitness UWP is free.

From the minimalist Store description:

Do workouts from plan. Write your results and achievements. Follow your progress in fitness. This app is useful for everyone, regardless of gender, and physical level.

Here's a brief walkthrough of True Fitness UWP:

A wizard asks questions when starting in order to tailor some of the recommendations within; (right) a graphical tips overlay introduces the UI.

The home view is your Calendar (optionally with your own appointments included), with fitness summaries for appropriate days shown. You can add notes or schedule extra exercise sessions; (right) working through a set of exercises in a session, they get ticked off as you complete them and enter the number of repetitions done, etc.

Each exercise has its own history, along with your logged weight (you'll be on and off the scales quite often with this app!); (right) there's quite a bit of detail included with each exercise recommendation, though some previous knowledge is assumed.

A muscle reference is good eye candy, pick the group and see it light up on the body shel (PS. don't select the 'female' option in Settings, as she's downright scary!)

Various backup and restore functions via OneDrive shown attention to detail, while rest days have this rather admirable graphic....!!!

Most things worked as advertised, though tapping through to the 'how to' panes produced blank screens - I think these are loaded from the Internet and some server or other is down. Oh well. You can grab this for free in the Store here, so give it a try if you're into fitness logging.