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 call it my own personal will. I know I wouldn't be able to do it if not for my kids. Almost all the time, I feel like giving up because I am too tired from work. However, if my children need me and I'm also not feeling well, I would automatically have that power to do things and stay up for long hours to look after my kids.