Option 1: Push through it.
I don't recommend doing this. In my experience, you will know if you just need to push through because you just don't feel like running today or if it's more than that. Rather than risk injury, take the day off. If you know you're OK, and you're just being a wimp that day, then pick an object in the distance and tell yourself to at least run to that. Another method I use it to start counting steps. It's rather hypnotic and often times, when I feel like throwing in the towel, buy the time I get to 50 steps with the left foot...I feel OK and end up running the whole way.Option 2: Take it as a sign that you need a rest day.
Have you been running more or harder lately? You could be over training. If so, just walk back and enjoy the rest of your day. But whatever you do, don't get discouraged. Tomorrow is a new day.Option 3: Change it up and do something different.
This is my usual choice. For example, today, when I wasn't feeling like a longer run, I just changed it to an interval session. You don't need a track to do intervals. I simply turned my workout to running hard for 1 minute and walking 1 minute for recovery. I repeated this for 1.5 miles today.Long story short, listen to your body but also be willing to adapt and change things up.
Happy trails!