Being a Christian doesn’t mean your life will be smooth and easy. In fact, Jesus said we’d encounter trouble and sorrow. It’s not always easy to be positive when hard circumstances come your way. Personally, I’ve had times when I didn’t exactly have a smile on my face.
The psalmists repeatedly encourage us to remember the things God has done. Even more, we can praise Him simply for who He is. He’s righteous, pure, kind, compassionate, merciful, faithful, patient to name a few. The apostle John tells us God is love itself. This, I believe, is what the writer of Hebrews calls the sacrifice of praise. When times are hard, the Holy Spirit will give us the strength if we ask Him.