Psalm 20

In Psalm 20, the "you" being prayed for isn't David or the worshiper but the promised messianic king, fulfilled in Jesus: his victory over sin, death, and hell becomes ours by faith, since our fate is in lockstep with his. That grounds three things: we rejoice because the King did all the work, we're confident because God's own name is staked on our salvation, and we trust him alone because everything else we could lean on has an expiration date.