Therapy can help
Sometimes symptoms of depression
can last for a long time; it is referred to as chronic when it persists for at least 2 years.
The good news is that treatment (medication/therapy) increases chances of getting better and staying better. In addition to therapy, individuals with depression often find The Mindful Way Workbook by Teasdale, Williams, Segal, and Kabat-Zinn helpful. Best to you