Fervently

Fervently – having or showing great warmth or intensity of spirit, feeling, enthusiasm

Based on that definition of fervently, I’d suggest our prayers to God should be said fervently. David Guzik once said:

Much of our prayer is not effective simply because it is not fervent. It is offered with a lukewarm attitude that virtually asks God to care about something that we care little about.
Effective prayer must be fervent, not because we must emotionally persuade a reluctant God, but because we must gain God’s heart [as our own] by being fervent for the things He is fervent for.

If we really believe in God, and believe He can answer our prayers. Praying fervently, shows we care about the prayers we are offering to God.