Self-esteem is your sense of self-worth. It typically develops before the age of 10 and is heavily influenced by the messages you received as a kid from your parents or parental figures. If one or both of your parents was distant, was working all the time, had a substance issue, or even if they just had exceedingly high expectations, all of these things could have negatively impacted your sense of self.
You can gauge your degree of self-worth by listening for the critical voice we all have in our head. This is the voice that says you need to stop being lazy, that you aren't working hard enough, that you are selfish, that you are stupid etc. For some people, that voice is a constant companion in their heads. If that is the case for you, here are a few things you can start to do:
1) Start to notice the critical voice. Spend a few days identifying your critical voice. What you will likely find is that it is constantly berating you. Sometimes you don't notice a voice but rather it's a feeling of guilt or shame. When you notice the critic, say "Oh there is that critical voice" - this will give you some distance from the voice because for most people, that voice sounds like it is stating facts in your head (e.g. I do actually suck).
2) Talk back to the critic. The next step is to respond to the critic. You can tell the critic to shut up or call it a liar. Think of the critic as a bully and the only way to stop a bully is to show it that you aren't afraid.
3) Practice the compassionate voice. This is the part that most people have a hard time with because they don't feel like they deserve compassion. Everyone deserves compassion. If you have a hard time thinking of compassionate, kind things to say to yourself, what would you tell a friend who was experience a similar thing? Usually, when we think of soothing someone else, we can effortlessly come up with kind statements but we struggle to apply them to ourselves.
So what does the kind voice sound like? The compassionate voice considers the context of the situation. For example, if you are sitting on the couch and there is a task you need to accomplish but you are struggling to find the motivation, your critical voice will likely yell, "Stop being lazy!" This type of command does not improve your motivation, it only makes you feel worse. Ask yourself, objectively, why am I having a hard time doing this task? Am I depressed? Am I scared? Does the task signify or represent something that worries me? Have I been sleeping well and do I have the energy? If you are suffering from any of these issues, you could respond to the critical voice by saying, "I am feeling depressed, and I am struggling with motivation, that is normal. I need to take care of myself". Talking kindly to yourself will feel strange at first but with practice, it will become more natural and internalized.
4) Break tasks into small steps. If you are struggling to do something and your critic is really active, try breaking the task down into smaller tasks. So, if you need to look for a new job, set a goal of adding two lines to your CV, or look online for one possible place to work. On the next day, you can add a few more lines or submit one CV. Doing this will make the task less intimidating; make sure you praise yourself each time you accomplish one of these goals.
5) Read about self-esteem. Here is one of the best resources I have found for self-esteem:
More strategies to improve self-esteem can be found here.