My first daughter was maybe high needs, but as she was my only one, it didn't really matter so much.
Both my twins were...well, maybe more fussy. Let's just say they needed LOTS of holding, LOTS of nursing, LOTS of attention, and even with that they were not terribly happy much of the time. So I just wanted to give my two cents:
As someone already said, I had to totally LOWER my expectations. Trying to meet the needs of my two year old and my needy newborns was ALL I tried to do. Obviously, I let go of expectaions for household chores, but also for sleep, adult conversation, personal reading or e-mail, MDC. I accepted that it was a temporary situation, I had to totally give myself over to the tidal wave I was riding, and that there would be an end to this stage of our lives.
And, getting the hang of double-slinging and then simultaneous nursing while lying down totally improved our lives. They were really life-changing "skills" for our household.