Carol Kivler's battle with mental illness — a battle she said she now wages every day of the year — didn't start with one particular event.

It wasn't until she began experiencing physical symptoms that she even realized she was facing mental illness. Kivler said up until the time of her diagnosis, she had no reason to think she was at risk.

"I recall vividly thinking: 'What do I have to be depressed about?'" Kivler said Wednesday evening during New Jersey 101.5's town hall on mental illness. "I have three healthy kids, a loving husband, beautiful home, money in the bank. What am I depressed about?"

Kivler said her psychiatrist told her it wasn't something about her life that was causing her depression, but a chemical imbalance in her brain. As she has gone through multiple rounds of depression, which have included thoughts of suicide, Kivler said she has learned to see the warning signs, which allows her to get treatment sooner.

The National Alliance on Mental Illness estimates 1 in 5 adults in the United States experiences mental illness in any given year — but many go undiagnosed or without help.

What separates a person being sad from a person who is suffering from depression can be difficult to determine. A person with depression may not show outward differences, but that can betray what they are experiencing on the inside.

Shaun Sweeney, the vice president of patient care at Carrier Clinic, said that while everyone does get sad at times, the physical impact of depression can be the most powerful warning sign of a greater problem. Sweeney said a person who is sad can generally continue to function normally, while a person with depression may be limited by their condition.

"When it gets to the point where it's interfering with your daily life is when I really think you should start thinking about talking to somebody about it to see if you can you know, get some help, get some changes going on," Sweeney said.

How long the bouts of sadness or depression last can also be a factor for determining when treatment is necessary, according to Philip Lubitz of NAMI-NJ.

"It impacts every part of your being," Kivler said. "For me, I don't even see colors that bright. Everything is gray and dingy for me. And then when I come out of the depression everything's so bright and I'm thinking, 'My gosh, what was wrong with my eyes?'"

Kivler said her treatment includes writing a journal, meditation, prayer and exercise. She also keeps an eye on her diet and the amount of sleep she gets. When her depression is in remission, Kivler said even her friends find it hard to believe it affects her.

For the past several years, Kivler has run a nonprofit organization called Courageous Recovery, which aims to help promote mental heath wellness and eliminating the stigma.

You can learn more about Carrier Clinic and NAMI NJ at their websites.