These things I have spoken to you, that my joy may be in you, and that your joy may be full. John 15:11 ESV

Amplified Bible
I have told you these things that my joy and delight may be in you and that your joy and gladness may be of full measure and complete and overflowing.
Hebrews 1:9 tells us Jesus was anointed with the oil of joy by the Father because he loved righteousness and hated lawlessness.   The Amplified bible expounds this verse to read, You have loved, delighted in, integrity, virtue, and uprightness in purpose, thought and action and hated lawlessness, injustice and iniquity.  We know from studying the life of Jesus this very character was displayed throughout his earthly ministry.  Jesus said in Johns’ gospel his desire was to teach those followers the things that would bring them into the full measure of His joy.

In society today, much emphasis is placed on happiness. A definition for ‘happy’ is feeling or showing pleasure or contentment.  Most of us spend the majority of our lives trying to control external circumstances to experience ‘happy’. Jesus’ personal circumstances were not always ‘happy’ and yet His joy was full. Happy has to do with external HAPPEN-INGS, and Jesus lived from the inside out.  Joy is internal.  Joy is a work of the Holy Spirit.  Joy flows from our connection with the Father.  Joy comes from living with a clear conscience, being and doing right in the Fathers sight.  From John 15:8 onward we read the foundation Jesus sets for fullness of joy "... My Father is glorified by this, that you bear much fruit, and so prove to be My disciples. Verse Just as the Father has loved Me, I have also loved you; abide in My love. If you keep My commandments, you will abide in My love; just as I have kept My Father's commandments and abide in His love."

Jesus has never given a commandment that He has not given us the ability to keep.  It just has to be done through the grace He gives and by the power of the Holy Spirit requiring us to be one with Him.  

The Pulpit Commentary states in regards to John 15:11, “.... the words are more simply explained by Lange, Meyer, Lucke, Westcott, Alford, and Moulton, as the communication to his disciples of his own absolute and personal joy. "The joy that is mine," like "the peace which is mine," is graciously bestowed. A joy was set before him, the joy of perfect self-sacrifice, which gave to his present acts an intensity and fullness of bliss. It was this, in its motives and character and supernatural sweetness, which would be in them. If they receive his life into them, it will convey not only his peace, but that peace uprising and bursting into joy; and he adds, in order that your joy may be fulfilled, i.e. perfected, reach its highest expression, its fullness of contents and entire sufficiency for all needs.”

From Jesus great intercessory prayer in John 17, we read from verse 13,"I am coming to you now, but I say these things while I am still in the world, so that they may have the full measure of my joy within them.

It is the intent of our Father for His children to live from this place of fullness of joy.