I find it interesting how many people around here have health problems that can easily add up with various stuff, including language learning, and result in the worse meaning of burn-out, the clinical one. I hope noone minds pointing this out, as some of us have shared a bit about the condition. Depression is a rather common example here.
That's why I find it hyperimportant and awesome this group supports the individual members in having fun. In language learning being a hobby, but still a meaningful one (because not getting any results is a part of burn out creation, not prevention of it). While we have very successful people here and people using the languages professionally, I am grateful we manage to keep it the "all language learning goals are awesome" way. And I'd like to thank everyone for participating!
Snowflake raises valid points here. The expectations of others affecting our own. It is tiring to have to always perform well or be taken for a fraud, or to disappoint someone. (I think this is even more pressing for autodidacts, despite the fact we often perform better than people in classes) I can't even imagine how hard it must be in cases like Snowflake's but I don't doubt this is not a rare situation. I've heard about similar stuff concerning latino people in the US who are expected to speak Spanish but they don't. The asian looking people may have it even worse, as people generally guess a wrong nationality and language.
Also the self-rewarding strategy is a good one. When it is hard to find intrinsic motivation, it is perfectly ok to go for extrinsic. In the case of the "it is not much fun now" kind of "burn out", it can help get through the difficult phases. In the case of the real burn out (at least the early phases, the fully showing ones should definitely be treated by a psychiatrist and/or psychotherapist), it can help survive. People are usually advised (by friends, family members, random acquitances) stuff like more activities, more social contact with people, sports and so on. That's the problem, because everything annoys you and tires you. You want to not wake up, so that you don't have to do anything ever again, not the opposite. However, buying yourself stuff (while it is a seemingly superficial kind of solution) like good coffee, nice colourful pens and pencils, good meals in a restaurant, all that can be helpful. I have experience with my brain under so much stress being much more able to appreciate such simple stuff than the complex things (like changing my whole life or doing more of the difficult things, like sports). It takes money, that is a problem. But that actually helps with not rewarding oneself without completing the task the reward is associated with.
I'm not sure if it's related to my depression (which I'm getting treatment for), really struggling with a difficult major back in college, or just a current difficult life situation--or maybe all three at once--but it's a common problem for me. 
I guess you could say I'm burned out from being a beginner? That's why at this point, I'm more likely to continue a language I already have a good base in then to start fresh with a tempting language. 
