HOW TO REPAIR or MODIFY GPX FILES w/ MISSING DATA (using BaseCamp and Excel)

Tutorial on how to repair GPX files that are missing data (because you forgot to turn on your watch/GPS device) or to repair corrupted GPX files. Using Garmin BaseCamp and Microsoft Excel, I will show you how to recreate the data and make sure it can be imported into Strava or Garmin Connect (or similar software).
WARNING: this is for advanced users only, requires some knowledge of Excel. This is also done on a Mac so Windows users beware.

[Rasteell]

Thanks for an excellent demonstration. It has been seven years since I had reason to use Excel for a significant project and it was wonderful to see a master at work.

[kathyclevenger]

This was awesome! I didn't have an old track so I just added elevation data similar to your adding time. Maybe could have downloaded a track. I used Basecamp to load to Gaia. Thank you.

[peterszasz]

Thanks, this was very useful! Small note: I had to use Google Spreadsheets, as the TEXT function was buggy on my Excel (which is very weird). Everything worked fine, and actually exporting to TSV (tab separated values) resulted in a simple plaintext file ready to use without all the text cleanup that would've been necessary from CSV. Anyway, thanks again, saved (the recording of) my trip!

[KickAssets]

How about a way to delete things? For example I ride for 4 hours...but when I retract the route I took..the GPX stops here and there as I stop to get water etc...or lunch...is there a way to go into the GPX file and delete those delays to make it ONE SMOOTH ride?