One of the triggers for me ending up at docs was lethargy, no concentration(don't laugh
), easy distraction and the lack of drive to do anything. Not to mention a pretty carpy environment and people at work. Theres another, but I'm not disclosing, which ultimately made me fall off the happy boat.
BP has the answer, exercise, but if you can't motivate yourself, its hard to get started. Docs will give you a sick note for a few days off to get you started, if you are really honest in how you feel, and don't hide anything.