Study Hebrews 4 and find out where you're at and ensure you mix what you hear in that passage with faith, setting yourself apart from how the world does things.
Faith and obedience = rest. Faith without walking in it brings death as evidenced by James 2:14-16. Trying to enter God's rest without faith accomplishes nothing but continued UNrest. Both are required: Faith in God's ability to give rest and actively stepping into it.
Making the decision to not only HAVE faith but to also WALK IN IT is a decision each of us have to make for ourselves. As we do, God becomes our guard and protector and we achieve rest. We can choose to walk in rest or choose to try and take care of things ourselves and have no rest. It's up to us. Neither way we choose changes the fact that every detail about us is known by a loving God who wants to take care of us. The problem is most of the time He can't because we've been too busy trying to take care of ourselves.
Every place of rest in God has a door through which to enter, and each of those doors has a threshold across it. God is guarding every door and will choose who He allows to cross that threshold. It is those who choose to listen to His invitation to enter His rest and combine it with faith who will be allowed in. You can look into the place of rest all day long and never experience it, but when you by faith choose to enter in and by faith step over the threshold is when you experience God's rest. Your faith in God's invitation and responding accordingly is your key.