At the risk of offending some folks (which is not my intention) I'm going to offer my two cents. These thoughts and feelings are very familiar to me. As someone who has experience with both addiction and depression, I now draw a distinction between passions / hobbies and distractions. Games, TV shows, drinking, etc. are, in my experience, more distractions than they are hobbies. The hobbies that have brought me lasting contentment tend to be things that bring me into direct experience with actual life, things that heighten my experience of the present moment, as opposed to things that take me away from that (even though those things often feel good in the short term).
For my 20s, my primary hobby was drinking and smoking pot. I also did well in school, got a job, lived overseas for 6 years, got a grad degree, had a few relationships, played in bands, and so on. I was pretty unhappy, though. I got sober when I was 29 (8.5 years ago). For the first couple of years after that, I spent a lot of time playing video games (as I always had done), watching TV, etc. I was still pretty unhappy. Eventually, I started developing healthier (for me, anyways) hobbies. I started hiking, running, biking, stuff like that. I started gardening and (after buying a home) doing DIY projects. In the last year, I got serious about meditation and joined a local mindfulness group. That, more than anything else, has helped my mental state. In general, though, I get much more contentment from hobbies that are beneficial (either for my health, a skill or something tangible) than simply distractions.
So I've made choices to reduce the number of distractions in my life. I play a lot less videogames than I used to (an hour or two a week, if that). I maintain this by having very old systems (PS2 and N64) and a laptop without a good graphics card. To be honest, I wouldn't trust myself around a PS3 or PS4. Similarly, I don't watch a lot of TV. I don't have cable, and my wife and I might watch an hour of something a couple of nights a week. I also deleted my Facebook account and quit playing fantasy football. Part of how I made all these decisions was simply by paying attention to how I felt. With Facebook, for example, I noticed that after 30 minutes on, I almost invariably felt worse than when I started.
Of course, I'm not perfect (and I wouldn't really say perfection is the point). My current distraction of choice (for the last several years, particularly when I'm not feeling great) is binging on comedy podcasts. Overall, though, I spend much less of my life distracting myself than I used to, and that has had a directly correlation to my contentment.
In terms of meaning, I'd say that as my overall mental / spiritual health has improved, this question has troubled me less. My immediate answer, though, would be something along the lines of service / helping others. That's the perspective from which I approach my job, and it has really helped. I don't do anything particularly amazing (database development) but I really try to approach it from a POV of "how can I make things easier for the people around me." In Buddhism (at least as I understand it), we don't talk about meaning as much as we do intention. And, for me, setting an intention like "I'm going to try to ease suffering for myself and those around me" at the beginning of the day can help me keep the proper perspective. And when I start to spin out about something, I can look at it in those terms. Like if I start to get anxious or depressed about something, looking at that situation from the perspective of what can I do to ease the suffering of myself or others in this situation often helps. Gratitude is another great practice for my mental state.
I've learned over the years that, for me, a healthy mental / spiritual state is something I need to work at. For some people, this comes easy, for others its a bit harder. Just like some people struggle more with weight than others. Ultimately, though, I've become grateful for this need, as my life has become much richer as I've developed these practices.