First, you want to tell yourself there is no going back, that is why wise folks burn bridges of the past so that there is no way they can turn back. With going back out of the question, you have solved like 50% of the problem.
When the going gets tough and various factors or forces swings in to halt progress, the first reaction is usually to turn back, back to familiar grounds, back to where we were coming from, back to the way things were. This is a terrible feeling and a terrible idea, once we head back, we lose everything and we will now likely settle permanently in the average zone.
Second, you want to remind yourself WHY you stepped out in the first place. What happened to you initially that made you venture out? What circumstances led to your stepping out? Fixing your mind on why you are out there, moving and seeking progress is a great booster to keep going.
Finally, you want to remember all the good things that has happened so far, the testimonies! Who has benefited from your work in the past and really commended you for the bravery? Every good remark people make about you should be stored up for times like this… When the going gets tough.
They say when the going gets tough, only the tough can keep going, but not necessarily. When the going gets tough, its the people who have decided there is no turning back and know why they are doing the things they do that will keep going. The others will turn back and join the applause crew.