Do you feel like this all the time, or just some days, or only recently...?
I know how you feel. It's hard because I don't know what life is supposed to be, but the older I get, the more I realize that life is exactly what it is now, and sometimes the now isn't very exciting...
I know everyone probably says this, but it sounds like you need an attitude adjustment. You can't always control your environment, but you can control how you respond to it. I just try to notice the small details that make life good (even just a good cup of tea or whatever, haha). Sometimes I have to fake it, but the more I fake it, the more real it becomes, if that makes sense.
I think anger and unhappiness can feed on themselves and grow worse and worse, so it's good you can channel it into working out. But yeah, I can relate. I've just learned not to think about it, because I prefer being happy about any little thing I can get...