Help with self soothing!

Maria
Ok, so LO is 3 months old today and I have always walked and rocked her to sleep!! Now, not only is it getting tougher the heavier she gets, but she seems uncomfortable too! But she won't go to sleep any other way! Unless we walk her on our shoulder for ever!!!! Anyway...I'm wanting to start easing her into self soothing and an easier way to sleep! Any ideas??