Times can get hard that you feel like throwing in the towel and can continue no more. This happens to all of us, in business, family, jobs, whenever we hit a wall in life. Quitting always seems to be the easier step but it is NOT. It only gives the difficult situation you didn't handle a chance to come back and hit you once again.
The most important thing to do before thinking about quitting is changing how you look at a situation. Chances are you've not realized the source of the challenge your facing which could be you. People tend to put the responsibility of something going wrong on others without looking at themselves. Try to look at both sides of a situation and own the blame if it points to you. And when you realize the problem is from the other end, calculate how to handle the matter to get the best results out.
Besides looking at things from a different angle, you need to find a different approach on handling difficult situations. You can't keep expecting different results when you keep approaching a task the same way. Change the techniques of handling a challenge to get better chances of solving it as you might land on the right solution.
Try hard in working out a solution for the challenge at your disposal, if everything in your power has failed to make it better, then call it off fast because that task was not meant for you.