Rest less often?
Nothing in the game requires you to take long rests.
I long rest as little as possible even when my main is a mage. (My first long rest is usually at the Druid Grove after I've defeated the Bugbear assassin and the Harpies.
It's your choice.
If you want your Warlock to shine a little brighter only take long rests after every 5 or 6 encounters.
