It might be a good idea for you to tackle the root cause of your insecurity.
If you can't think of what the trigger for your insecurity is then perhaps some form of counselling could help you remember. In fact counselling in general might help you.
Insecurity can often be the result of a lack of confidence too.
Fortunatley for you all these things can be worked on as long as you recognise that they're your own problems to own. Which it sounds like you've done.
In the short term, having a mantra that you repeat to yourself every day in the mirror three times in a firm voice might help, (you are going to feel like a complete plum doing this but you'll get used to it). Something confidence boosting... heck, you can even use 'cause I'm worth it' if it does the business for you.
Another little trick is to walk around the street/room/ anywhere as if you own it. If you can act confidently you will become more confident. (Or at the very least not look so needy).
But find someone to talk to and explore where your issues come from. It's likely to long, hard work and unpleasant. However it will be worth it in the long run. Good luck.