I often visit nature at sunrise, or sunset. It is the point where light transitions to darkness, or darkness to light. There is never a moment where I can see the transition. There is not a time where light ends, and darkness begins. The scenes flow, and the change is a matter of degree.
The same is true for hot and cold. The trail can start out cold, but warm up. I can generate my own heat when climbing, or descend in to a cool valley and feel a chill. When does cold end, and hot begin? From these examples, we can understand that opposites are really the same thing, the differences being simply a different point on an infinite scale.
By observing nature, we can understand this concept and apply it to our own emotional states. Our emotions manifest along a spectrum, like hot and cold, light and darkness. As we hike along the trail, we may notice different degrees of elation, awe, or joy. We may also experience degrees of physical change, and feel more or less fatigued or vitalized. We can understand that fatigue can be transformed to vigor through rest, refueling and hydration. We make an effort to transform a physical state along the spectrum by first contemplation, and then taking action to move along the scale to the desired state. Fatigue becomes vigor through thought and action. Fatigue and vigor are the same thing, they just differ in degree.
Dark becomes light by adding light, not removing darkness. Cold becomes hot by adding heat. Opposites move along their spectrum and eventually meet. Go far enough along any scale of opposites and you find yourself back at the start. Go far enough east and it becomes west. So the difference between any opposites is simply a matter of degree. Everything has its opposite, and opposites are really the same thing.
With that understanding, we can see that love and hate are the same thing. We can connect sadness to happiness by seeing them along a vast spectrum. All emotions have their opposites, and we are often swung wildly and uncontrollably through emotional states by being influenced through the thoughts and actions of others. But, by being aware of the polarity of nature, we can also understand and be aware of the polarity of our emotional states. We can take action to change our states by focusing on the opposite place on the emotional spectrum. Escape sorrow by focusing on joy. Eliminate hate by living in love. Slide along the scale of angst and depression by moving towards vitality and hope. Joy lives in nature. Love, vitality and hope exist all along the trail. Move away from the sources of dark by stretching and reaching toward the light in life. Surround yourself with vitality and energy. Create the conditions of growth and contribution in the forest of your mind, and direct your thoughts and energy to become the sunlight.