If you wish to change then start somewhere and keep at it. To change behavior, you can change the way you stand, your posture and alter your chemistry, you can improve your diet or give up an addiction or any number of little and big alterations.
One of the most significant texts, The Yoga Sutras of Patanjali, lists four perquisites to improve your life. Both happiness and sadness are guaranteed in your life. Building your inner strength allows you to have equanimity with regard to either, that is, to have evenness of temper even under stress. But even more so it is important to make choices that are more likely to lead to balanced outcomes for you. These choices are on a moment to moment basis with regard to short and long term issues. The parameters need to be simple if you are to have any hope of allowing them to be part of your daily choices.
The four behaviors that predispose you towards happiness are Friendliness (just be polite, end generous), Dispassion (don’t take things personally), Compassion (see events from someone else’s point of view) and Non Envy (do not envy or desire something possessed by somebody else). These behaviours are no guarantee of happiness but they certainly will help you to move in that direction.
If I look at the list above the main trait that brings people undone is Envy. If you are envious of others’ talent and success you will undermine your relationship with them and with yourself. In fact allowing and helping others to succeed without rancour allows you to have a successful personality.
So how do you go about changing your way of behaving and particularly controlling your impulsive or habitual behaviour?
The Alexander Technique, Yoga and Pilates, amongst other disciplines, teach us that bad posture, both physical and mental, can be improved in many ways. It takes time and in time you can learn to recognise habitual stances, physical and mental and emotional, and even though they may be familiar and comfortable in the short term, (compensating for an imbalance) in the long run they are often destructive. To correct them you must learn to recognise more balanced stances and when the old habit arises inhibit your impulse to go straight into it and allow, say the neck to lengthen and allow that lengthening to affect the way you carry your spine or be still when you would normally reactively move.
This idea applies especially to behaviour. In my family of origin I assumed many stances and attitudes both physical and psychological to protect myself. Mostly they consisted of avoidance and suppressive behaviors. For example looking people in the eye was hard because to look someone in the eye can challenge them. I didn’t feel secure enough to challenge anyone in my family. So I often felt that normal engagement of eye contact discomforting.
It is healthy to be able to meet someone’s gaze, so now when I am in that situation and feel the familiar anxiety marked by gut pain and chest tightness, I’ve learnt to allow the sane gaze of other people in and feel secure. In this way you can gradually start to make healthy and honest contact. Genuine contact with another human is your birthright. Your fears are your greatest teachers of self awareness.