In 1 John 3:22 the apostle links confidence in prayer to a good conscience, and now he links it to assurance of faith. The Lord loves us as individuals; our prayers do not have to break down great barriers of reluctance within him but only to humbly place our needs before him, and he is ready to bless us in response.
If the Spirit is in us, the things we will desire most are the things which advance his kingdom and therefore this great freedom in prayer is safely given to those who love God. This is the freedom which every child has in asking his father and it is precious to the father because he wants the child to come to him with requests that are important to the child.
It is a serious misunderstanding of this verse that says, before we can make our requests some prior step is required in order to discover whether what we ask is his specific, secret will or not. No such procedure is described in Scripture.