Every one of us is gifted with the capacity to build our thought process and accordingly your attitude will depend whether it is positive or not. We all must realize that we have the full control over our behavior and we control our surroundings.
Our mind perceives everything that it sees, as a result if we are in negative environment or under the influence of people having negative mindset, we start learning those things and loose control over our mind completely. Further loosing control from mind leads us to involve in destructive activities.
Yet you must know the fast we pick up these negative thoughts, faster we can get rid of them. All we need to do is to pick them from our mind and throw them out. Else you will keep on spreading similar mindset in your surrounding.
Hence try to cultivate positive thinking rather than getting trapped in to the vicious cycle of negative thoughts, for this just spend time in the company of positive thinkers. If you cannot get one, then just shop for some good CDs and DVDs, attain lectures etc to maximize your potential of acquiring positive thinking. But your work does not finish here; you need to practice it on daily basis, till you feel that no negative thoughts can haunt you any more.
Meditation is one such way by which you can easily attain a state of positive living and thinking. As it helps you to focus on your goal and prepares your mind for the same, making you feel relax. Additionally, meditation also helps in keeping your body fit.