Secondly. Next time you are in a neutral or negative state, start breathing at the rate and rhythm from the first exercise, and within a minute or so, the positive state should begin to return.
Many gurus advise people to do breathing exercises regularly. I know Tony Robbins does in his marvellous book 'Unlimited Power' he advises that you start each day with a breathing exercise of inhaling slowly and deeply, then holding it for twice as long as the inhalation and exhaling in twice the pace. It really is invigorating and a great way to get motivated at the start of the day, especially if you are looking to do some things with your day that require motivation.
Breathing is powerful, our life force and is a major factor influencing our state of mind (if you uncertain about this, hold your breath for two minutes and re-read this sentence). This being the case, please use your common sense when doing any of these exercises. (If you have a respiratory condition, please check with your health advisor first. I do not want any asthmatics complaining that they did themselves harm following these exercises!!)
Thirdly. Start breathing comfortably but deeply, in through your nose & out through your mouth. Imagine that you are breathing from that area of your abdomen just beneath your belly button. Make the in-breath last to a count of 5 and the out-breath to a count of 6. Continue for at least 2 minutes, and notice what happens.
This 5:6 ratio seems to be a simple yet powerful way you can induce a relaxed state at will. The art of Yogic breathing is called Pranayama. Pranayama offers many different approaches for cleansing the mind & body through breathing exercises. Here's one of them (with thanks to RA Wilson):
Fourthly (this may seem a bit odd to do, I'd recommend not doing this in front of friends or at work!). Lie on your back & pant like a dog, breathing rapidly in & out through your mouth 20 times. Then, breathe slowly, deeply and gently in and out 20 times through your nose. Once again, do the mouth-panting 20 times, then resume gentle nose-breathing. Notice what happens. This technique is referred to as the breath of fire, and typically results in a state of... well, you'll find out!
Please remember that most people don't breathe nearly enough. Start to breathe more deeply and notice how much better you feel. Have lots of fun with this. Notice how good you can make your self feel when you breathe differently.