I'm not ecstatic all the time, but I'm generally positive and pretty happy with life.
Exercise, prayer, meditation.
In general, these seems to work. I am a big advocate for any form of yoga, as it incorporates all these elements.
A big one: deep breathing.
We can expand Vital Capacity of the lungs in 2 ways: prolonged aerobic exercise and deep breathing. More breath=more oxygen=more ATP=more energy. A basic, but effective, exercise is this: inhale 4 even breaths through the nose, so that you fill yourself completely, exhale through the nose over 2 beats (at first you'll probably get 3.5 breaths - keep trying to inhale and you will slowly increase the maximum capacity - the goal is even breaths, find the balance between how much you can take in and the ease of breath as going to fast can cause tension- remember that the breath is low- inspiration through the diaphragm). Do this for a minimum of 3 minutes. (ideally in easy pose or lotus, but it works great in traffic too)
If mantra helps you focus: sa ta na ma, waheguru
(roughly: Infinity, Life, Death, Rebirth - ecstasy [through] ultimate-reality)
I find most anxiety and sadness to be responses to things out of our control. To remind ourselves of our inner world and to claim control of the immediate self, through the breath, we can live "happier" lives.