avoid negativity

In life, we meet many people. Some of them we meet are successful in their life , some are failures, some are happy, some often complains. i have observed various persons and i have found two type of peoples       first type is of those, who have a lot of work to do, lot of problems to face, they go through different struggles and finally reach their goal.       the second type of person are those who often  complaint and despite of all facilities proves nothing and just blame their luck.   what is the difference? after thinking on that , I came to the conclusion that the difference is of their mentality. The person with positive mentality often face all hardships with a smiling face and become successful while the person with negative mentality, inspite of having all facilities proves worthless. So, the need is here to avoid mentality which brings negativity.  Now the point is that how to avoid negativity?...