But, I would also add getting even modest regular exercise can make a massive difference. Even just 1 hour a week split over 3-4 days can also dramatically change mood and energy levels.
Exercise (especially bodyweight exercise, which you can do pretty much anywhere, without any equipment) can be a sort of free, always available destress button. Whenever I get really stressed these days, I have the option of just putting a lot of the wound-up, stressed-out energy in to some exercise (like pushups) and it's amazingly effective.
I've never really realized until recently just how much of this mental stress I've been experiencing my whole life was so intimately connected with my body and how much physical things such as diet and exercise can affect it.
On that note, I could be totally off and the OP might just be regular old stressed, but there's no way anybody can really tell from this post. Everyone will project their worst experiences onto it.