The problem is that it's really difficult to explain, but I'll try.
The feeling of being a superwoman because you have gestated and birthed a human being (however the baby is born) - birth was difficult and not in any way joyful but I honestly felt that I could do ANYTHING after I did that. And mothers who have c-sections may not feel the same way but they have still created a human with their own body; it's a bloody miracle.
The feeling of overwhelming, unconditional love for your child. It makes any other love you have felt for anyone else before pale in comparison. There is endless joy in looking at them, cuddling them, smelling them (yes I still love to sniff my kids' heads and they are not babies
), hearing their voices; talking, singing, laughing. There is endless joy in witnessing their joy at discovering the world - the pleasures and fascinations of life - and watching their delight and pride as they learn all sorts of skills and discover what their bodies and minds are capable of. Events like Christmas, Easter and birthdays become magical because you're creating the magic and when you see their excitement and joy, it makes your heart burst. And the strength of the love they give back to you in return - you are the single most important person in their world (at least when they're little). When they spontaneously tell you they love you, or draw you a picture or write you a card telling you that you're the best mum in the world.
My favourite things are the sound of my children laughing, moments when I see/hear them interact with each other in loving ways (they fight a lot but the nice moments do happen), and the rare moments when they bundle into bed with us without elbowing or jumping on anyone and we have a massive hug and I just think this is it, this is what it's all for.