It is absolutely not true that only weak people battle with serious depression. Seeking help with depression does not mean that you are crazy or that something is wrong with you. It doesn't mean that you can't handle your own problems. It's just smart. Getting help when it's needed is a sign of strength and intelligence, not weakness.
Successful people know when to seek expert advice.
Most depression is usually relatively minor, but sometimes it can be quite serious and may have its roots in a treatable biochemical imbalance. If you are experiencing extreme or extended bouts of depression, get professional help as soon as possible. Generally speaking, depression responds very well to treatment, and usually does so in a fairly short time.