Fellowship is sharing in our common life in Christ with one another.
We engage in fellowship by relating to one another in oneness of heart through various means of serving each other in love.
If you have any encouragement from being united with Christ, if any comfort from his love, if any fellowship with the Spirit, if any tenderness and compassion, then make my joy complete by being like-minded, having the same love, being one in spirit and purpose. Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves. Each of you should look not only to your own interests, but also to the interests of others. Your attitude should be the same as that of Christ Jesus: Who, being in very nature God, did not consider equality with God something to be grasped, but made himself nothing, taking the very nature of a servant, being made in human likeness. (Philippians 2:1-7)
Fellowship is not:
standing around talking with a cup of coffee in your hand
a one way street wherein one believer gives to or helps another
the mutual, reciprocal sharing of our life in Christ
the fulfillment of the one another commands of Scripture