Fitness app not connecting to watch no matter what

At this point you need to isolate the issue. If you have access to family member’s or friend’s iPhone try pairing your watch to their device and see if the issue remains. First follow the directions to the link below to fully reset and un-pair your watch from for your iPhone.

reset and disconnect Apple Watch:

https://support.apple.com/en-us/HT204568

Then connect your Apple Watch to their iPhone using the directions provide in the following link.

connect Apple Watch: https://support.apple.com/guide/watch/set-up-and-pair-your-apple-watch-with-iphone-apdde4d6f98e/watchos

If the issue remains then there is a good chance the watch has an issue and you should contact apple support:

https://support.apple.com/watch

If the issue is resolved then you probably may need to reset your iPhone and “set up as new”. Restoring the iPhone from backup may reintroduce the issue.

To summarize:

• test Watch with another iPhone connection and see if issue remains
• if Watch works properly on another iPhone connection (other than your own iPhone) then either investigate further with apple support or reset and erase your iPhone (set up as a new device while not restoring previous backups).

Please report back with your results and the resolution so others may benefit.

Note: prior to reset do perform a current backup in case you find it necessary to restore data. If you use the iCloud and it is currently syncing things like photos, messages, contacts, etc then that data should sync back to your iPhone when you sign into iCloud on setup of your phone. If you are uncertain about how to preserve and restore data then consult with apple support before wiping your iPhone.

More info about iCloud and syncing:

https://support.apple.com/guide/icloud/set-up-icloud-on-your-devices-mmfc0f1e2a/icloud

Are You familiar with: watch complications and customizing/loading watch faces?

This link may help you either add an “Activity” watch face or add the “activity” complication to a custom watch face of your own.

https://support.apple.com/en-us/HT205536

Make sure fitness tracking is enabled (or toggle if it is enabled) on both devices:

on iPhone: settings -> privacy -> motion and fitness

on Apple Watch: settings -> privacy -> motion and fitness - > fitness tracking

Let’s start with some basics.

First make sure Bluetooth is “on” (on your connected iPhone).

while in Bluetooth settings (on your iPhone) check and to see if your Apple Watch is listed among your Bluetooth devices and says “connected”.

What OS version are you currently using for the Apple Watch and iPhone?

To make sure we are on the same page, what exactly to do you mean "fitness" is not on the watch? You don't see the app with concentric rings on the watches home screen (not watch face)? Would you upload a screen shot or take a picture of your watches home screen?

Both iPhone and watch should be enabled. If they were both enabled then toggle from ON to OFF and then back to ON.

Then reboot both the iPhone and Apple Watch

And your iPhone's model and OS?

I realize you may have done some version of this:

https://support.apple.com/en-us/HT204568

Make sure Apple Watch and phone are next to each other when unpairing and erasing the Apple Watch.

the repair Watch and set up as a new Watch (restoring Watch from previous backups may reintroduce the issues you are experiencing).