I have noticed that I can be having a really good day and be emotionally hijacked by something from my past arising within me and clouding my experience. It may result in minor negativity or cause total turmoil. It could even be a positive impact. The key point is that my current state is suddenly changed from within, not at all related to my external world. Sometimes the bubbles of emotion come in clusters, really upsetting my equilibrium; other times they occur singly. Each bubble arises with my awareness growing as it nears the surface, and then it reaches the surface and pops. Its contents then become part of my current experience. Like real bubbles that carry gas and scent from the bottom of a lake, the bubbles from within are more intense in their moment of bursting, erupting emotion linked to some past experience into our current world.
At such times I find it best to recognise and acknowledge that I am working with emotion from the past, and process the associated feelings through journalling, talking with my partner, or some other means that enables me to accept and release the emotional eruption. Even positive emotion bursting on the scene needs releasing otherwise we are losing our connection with the present and are being dragged back into the past. The most important thing is realising and accepting it is a natural part of life. The past does reinsert itself from time to time without provocation. It does not signify that we are stuck with an old issue or have some fault with our emotional world. Our psyche naturally lets go of it rubbish, its own cleaning process of our attachments to the past, and when it does we get to deal with it in our current state.