The horse represents the journey of our life. 
We are always running for our destiny, towards our calling. 

There may be distractions, but if we are in the Holy Spirit, everything is possible.
(Hebrews 12:1)

The running horse also represents breakthrough in our lives. 
Therefore, since we are surrounded by such a great cloud of witnesses, 
let us throw off everything that hinders and the sin that so easily entangles, 
and let us run with perseverance the race marked out for us.