There are so many reasons why kids might appear sad or unmotivated. Often, its not clear what to do. There are things that you can do to help. And, you might even be surprised how making certain changes which might even be fairly small, at least to start, can make all the difference in the world. Take a look at this: https://www.etsy.com/listing/599596945/the-essential-life-planlife-skills-full
There's 3 activities. Each of them are really important. But when the sad or unmotivated child begins to work on identifying their core values (this is the first activity), it marks the beginning of a generally very positive change in them which you might even notice.