The name first appears in Genesis 17: 1, when God says to Abraham, "I am El Shaddai." It's in the context of God promising Abraham something impossible (a son) - something that Abraham had ill-advisedly tried to achieve by his own efforts. God wanted Abraham to know that He is the Almighty, the all-sufficient One, able to do the impossible without any clumsy attempts at "help" from our side.
He introduced Himself the same way to Jacob (Gen 35: 11), another one who had foolishly tried to bring about God's will in his own way. Jacob was deeply impacted by that encounter at Bethel and still spoke of it in his old age. Towards the end of his life, he blessed his son Joseph in the name of El Shaddai. (Gen 49: 25)
This understanding of God as an all-powerful, all-sufficient God carries into the New Testament, expressed by the Greek word Pantokrator. Several times in the visions of Revelation, we see Him worshipped as Lord God Almighty. A well known example is Revelation 19: 6 - Alleluia, for the Lord God Omnipotent reigns! (Kyrios Theos Pantokrator)
It's a reason to approach and worship God with reverence and awe; not a reason to keep Him at a distance. One of the paradoxes of our faith is that we can recognise God's incredible power, we can realise that He doesn't need us, yet He longs for relationship with us and invites us to draw close, right into His presence.
In Psalm 91: 1, Moses recognises God as El Elyon (God most high) and El Shaddai (the all-powerful God), yet speaks of dwelling in His presence, close enough to be covered by His shadow; he's discovered that we find rest if we shelter in the "secret place" with God.
Because we know the God of unlimited power, we can also trust Him with the impossible situations in our own lives. I can think of at least two things in my life that seem impossible right now. What about you?
Let's stay in the shadow of El Shaddai and trust Him to handle the things that are too difficult or impossible for us. Nothing is too hard for Him.