Generally, a pear tree will bear fruit when it is four to six years old, depending upon the soil conditions and the amount of rain and sunshine the tree receives. It takes time for the tree to be mature enough to make fruit.
With us, when we become Christians by trusting in the Lord Jesus, His Spirit comes to live inside of us and God begins to do an "inside-out" work of making our character more like Himself. It is this work of the Lord in us that produces fruit on the tree of our lives.
Everything that is not consistent with the character of the Lord Jesus will be pruned away and everything that is consistent with His character will be cultivated and nurtured. He is the Master Gardner and He has a plan and a purpose specifically for each one of us. He wields His shears carefully and only removes that which is contrary to His plan and purpose. He is a tender Gardner and loves and cherish that which is to remain.
"But we all, with open face beholding as in a glass the glory of the Lord,
are changed into the same image from glory to glory,
as by the Spirit of the Lord."
(2 Corthians 3:18.)