"May the God of hope fill you with all joy and peace as you trust in him, so that you may overflow with hope by the power of the Holy Spirit." - Romans 15:13
Pessimism is overrated.
Relentlessly positivity is not about optimism. It's a choice, a constant attitude. Being relentlessly positive means deciding not to allow circumstances to rule my emotions or mental attitude. I choose to see no problem as impossible, every challenge as an opportunity to learn, and practice joy in every circumstance.
After all, if I believe some dude called Jesus died for me, I have no excuse not to choose joy even when life sucks sometimes.
"Be joyful in hope, patient in affliction, faithful in prayer." - Romans 12:12