How do you manage to take care of your baby when you aren't feeling well and there's no one to assist you?

I guess mommies are really blessed with "reserved strength" for cases like this. Like for me, I just think that no one will do it since it's just the two of us and my baby needs my care. Even if I really feel weak, there's something that's pushing me to stand up whenever needed (like when the baby cries or needs diaper change etc).