Negative thoughts flow into our brains all the time. It is important to acknowledge them not as tangible definitions of who we are but as not reality and just a part of a biochemical process that we aren't in control over. I have been through a period of depression where I fell into the trap of ascribing too much meaning onto thoughts that were irrational and that did not reflect how I behaved or my character as a human being. My irrational negative thoughts only served to perpetuate a low sense of self worth and a false sense of identity. Here are a couple of steps that help to deal with incessant negative thoughts.
1. First be aware of your inner critic. Awareness is curative so make sure when a negative thought pops into your head acknowledge it as what it is: a random biological process that does not define reality nor has any tangible significance in its own right.
2. Change it by offering your brain positive alternatives. For example, if you say to yourself, "I am a lazy person", re-phrase that thought into something that is true like, "Sometimes I can be very productive". Don't let negative thoughts define who you are, be creative and positive with your inner life and choose to live on the brighter side of life.