There are many ways in which we can self-sabotage.
Our subconscious minds buy into certain cognitive distortions. Simplified, this means our subconscious tricks us into thinking something is true when it's not. For example, when we make a mistake, a cognitive distortion would be our thinking, "I never do anything right!" The way to combat this type of thinking is to identify and label the thought/emotion, and combat it with logic. For example, "I'm thinking that I never do anything right, but I just made a mistake. What can I learn from that mistake so I don't make it again?"
Often, self-sabotage comes from a lack of self esteem. There are two good ways to help boost self esteem: The first is to write down one or two things we love about ourselves every day. It can be as simple as, "I have beautiful hands," to, "I am an outstanding problem solver." The second is to create situation in which we "win." For example, if we feel we're not good people, we can hold open doors for strangers, smile at others, or pick up trash we didn't drop. Now the message we tell ourselves is, "See? I AM a good person! Look what I did!" Then mentally pat ourselves on the back for doing such a good job. Our self talk is important; often that's a key to self-sabotage.
Another strategy for dealing with self sabotage is to be mindfully grateful. While being aware of our thoughts, feelings, and environment, we can also find wonder, amazement, and gratitude for that particular moment. It's not helpful to remember past mistakes and trauma, since it's in the past; it's not helpful to worry about the future, since it isn't here yet.
For example, we can notice and appreciate everyday things - like the water that magically appears from the tap, the incredible technology that is around us, and the wonders of engineering that enable us to hurtle down the highway at 60mph.
Being grateful and awed by what we have right now changes our perspective. We begin to notice the "everyday miracles" that happen all the time - and the need to self sabotage is reduced, since we're experiencing a wonderful by-product of the journey of life: Happiness.