How can you build up low self esteem?

Try to work towards realising that you have value and good qualities. Treat yourself with kindness and don't be so hard on yourself, we are our worst critics and it's easy to fall into self-hate, especially if we've been bullied or abused in the past. You can even take up volunteering, because helping someone else not only offers a distraction but it also affirms that we are good for something and that we have strengths that are needed. You can also try to make a list and stick this up somewhere to remind yourself, and keep reminding yourself because you might deny or ignore your efforts at first. However, in time when you become less critical of yourself and more patient, you'll see that you're only human and even if you make mistakes, you still deserve to be happy and valued. Having family or friends around you for support will also raise your confidence level.