In a pre-child life, if someone were to ask me what I got up to at the weekend and I replied that I went swimming and to the supermarket all in one day, the person asking might look at me as if to say 'and...?'. With children, doing two different things in 24 hour period is something to be proud of. Medal-winning territory.
Babies are incapable of self soothing or self settling in the true sense. Sure, they can suck their thumb, stroke a lovey or take comfort from a dummy/pacifier. This is their limit though. It's like 'self soothing lite'. This 'self soothing lite' requires the baby to be in a position where everything is fine.