1 John 5:3 (NIV)
This is love for God: to obey his commands. And his commands are not burdensome
The life of a Christian is not always smiles and happiness, but it is all joy. The Christian does not carry a heavy burden. If you find it difficult, something is not right. Most likely it is the love for God part which is connected with the not burdensome part.
Matthew 11:30 (NKJV)
For My yoke is easy and My burden is light."