Great day to run

Today I ran to [This has a different meaning] up the mountain, it and was very hard strenuous because it is very upright, steep.  Still but it's was relaxing.

This is the mountain of on my island. The orphan sentence has no bearing on the rest of your paragraph.  So it is better to leave it out. but I didn't run make all the way to the top not only because it's very far to reach but too steep to do so.  Its peak is at 2000m high.   and very high to run (2000m.) because later I have to back :) Also it would take too long to get home considering the return trip.

The route was is very interesting. , I had to walked through two municipalities and about eight kilometers. It was just because I'm injured, ????  Makes no sense.  Just now you ran up the mountain and now you have to walk?  Did you injure yourself during the run?  So I don't know how to correct.  A grammatically correct sentence doesn't mean that it makes sense - like in Mother Goose rhymes.  but for when November comes, I will be ready for the half marathon.