Plenty of unnecessary negative thinking arises from the belief that “bad stuff” happens and derails you from your goal. This isn’t true, and life is not some sort of straight upward trajectory with a clean point A, where you are, and point B, where you want to be.
Wherever you want to be changes constantly, and these attachments to ends cannot be relied on. The problems and obstacles that arise in your life are your life. They must be embraced and burned as fuel for your journey. This highlights another important facet of remaining in the present moment.
To the mind that is fully mindful and present, all obstacles become opportunities. Problems are simply part of the work of life, not these massive burdens that “ruin” your life. Imagine how boring daily living would be without little challenges. No one would do anything or go anywhere.
Instead of letting obstacles drag you down and prevent you from acting, let them catalyze the changes that are immanent in your life. Let these changes and obstacles come to you, and deal with them calmly. Meditation enables you to confront obstacles in this way. It teaches the mind not to judge its sensations but to simply deal with reality as it is, in the moment.