I find my self yo-yoing from happiness to depression, it feels hopeless, what do I do?

By accepting that life is a seesaw with ups and downs. We can influence how wild the oscillations feel - both through acceptance and practical tools such as diet, meditation, rest, exercise. And that - ultimately - we can experience our Self as the pure awareness in which the seesawing of life is experienced. A place that is calm, peaceful and untouched by anything that happens in the material world.