Have you ever been in a slump? Maybe the market is down, your industry has changed, your company is having "issues" or you've had personal changes (birth, death, divorce, move, etc...). Whatever the reason, you've been in a hole and you just can't seem to get out.
It can take just one thing to turn everything around. Oh- you want to know what that "one thing" is? Sorry- there is no magic answer because it's different for everyone. In business, it tends to be an increase in productivity. You're starting to meet some people, schedule appointments and you can see that things are starting to happen (even if you're not reaping the rewards, yet). Several years ago, as a realtor, I heard it said that "Realtors don't die, they just become listless." That same thing applies to most business. People with appointments on their calendars don't quit. They just don't.
What do you need to do to fill your calendar? Do calls not seem to be working? Get out where your customers are. Meet other professionals in your field and network to see where they are meeting people. Meet professionals in a sideline field. You may have information you can both share and benefit from.
Does that "one thing" solve everything? No. But it can help propel you to the next "one thing" and the next... and the next.