How can you cope with negative thoughts and borderline depression?

Many steps: First get a psychiatric evaluation. If the depression is rated mild to moderate, consider opting for psychotherapy with or without meds; if it is moderate to severe, consider meds with psychiterapy. Work on getting into an aerobic exercise habit and into widening and strengthening your social networks. Hope this helps.

CBT: Seek a psychological assessment. Cognitive behavioral therapy is excellent for these types of issues.