DS is 11, and usually a lovely boy, but in the last year or so he's gone increasingly emo on us... lots of "I'm feeling sad" and very little enthusiasm for going out and doing things, or trying anything new.
Any little thing at school gets him worried - for example, he has two quite small roles in the Year 6 play, and he's been fretting over it for a week or more. Ditto about homework, Sports Day, school projects... it doesn't seem to be subject-dependent, or related to the actual importance/likelihood of failure. He just mopes and mopes, and when I try to get him to see the positive side of things, he just says, "I don't know how." At times, this has translated into stomach cramps/sickness, which he saw a counselor for a few times, but she seemed to think he was fine. 
Doing things with the family is equally like pulling teeth problematic, which drives my husband mad. Nothing ruins a nice walk in the country like a moaning preteen! Basically, if I'd let him, he'd just sit and play computer games/watch YouTube all day long (we don't actually let him use screens all day, BTW, though he tries to push the limits of his time as much as he possibly can.)
Summer is coming, though, and I'm plotting ways to try to pop him out of this negative-thinking habit.
First up, though it's going to be absolute hell painful, is going to be at least a week's holiday from the computer. Reckon it'll be about as nice for me as childbirth, but I'm hoping it will give us some insight into how much of his mood is screen-related. (I suspect that Minecraft bloke has a WHOLE LOT to answer for.)
Second, he's going to have to choose a sport/physically active thing to do regularly. This is already a rule during term-time, but I'm going to push it harder over the summer.
Lastly, I'm going to give him proper chores to do, so he feels like he's contributing to the family. We've been very lax about this in our house - he pitches in with dishes, etc., but very much on an ad hoc basis - so I think it's well past time for him to get stuck in.
Anyone else in this position, and if so, what have you tried that has made a difference? I know some of it is undoubtedly the beginnings of teenage hormones, but surely there's something I can do?? 