"It's hard to give love to others if you can't give it to yourself; and your heart cries out for love.
When it comes to loving others, it makes sense that, if our feelings toward ourselves are unkind, any effort to be kind to others will be adulterated. These efforts will always be colored by some form of neediness. Either we will try to get validation from others or compensate for our lack of self-worth by being extra 'good.' These external efforts will never succeed as long as our inner world feels barren.
And it's that very barren feeling inside that makes us think we don't deserve love. We look inside and see anxiety and sadness; worry and stress; irritation and judgement. Then we equate feeling bad with being bad. In this formulation, if we are bad, then clearly we don't deserve love.
Instead of self-judgment, metta encourages us to care for ourselves simply because we are suffering, to be kind to the sadness and worry; to be gentle with the judgement and irritation. We actually give love to those very feelings. Rather than fighting with our inner life, we open to it with acceptance and compassion."