Taking care of your voice is the first priority of every singer. From the first lesson to your last performance, learning to sing well is learning to sing sustainably.
Get into the habit
Get into the habit of warming up every day, and certainly before every rehearsal. Even five minutes can help strengthen and prepare your cords for the day.
Go a little further
If you're warming up for a lesson, performance, or rehearsal, this is a good follow up to the first video. Careful not to push your voice too far too early.