I find I go through ups and downs as well. My ups generally occur when I accomplish something, when I work on something meaningful, when I help others, when hard work gets acknowledged, when I learn something new, when I influence change, when a complaint or a concern doesn't go unnoticed, etc. The downs on the other hand are primarily connected with feeling of helplessness, often due to restrictive hierarchy and bureaucracy, staleness (same work every day), status quo, frustrations that go unaddressed, etc.

edit: tuning out, punching in/out (ass in a seat), meeting expectations for me are all signs that point to me being stuck at a job without much enjoyment. Not being vested in the company is a tricky one though - I am ready to make certain sacrifices for a company, however I will always ensure I have a backup strategy. The same should hold true for companies as well.