My quick recommendation is to change things up. Start introducing some pilates as something slightly different but still complementary to yoga, or get into another form of totally different exercise, boxing or weights or any of those other gym things. I was about to recommend some classes, but then I spotted your thing about social anxiety - I’ve only got a bit of it, but gym classes usually freak me out, too.
Being trapped with ferociously inquiring mind but simultaneously being kind of physically lazy, I’ve spent a great deal of time talking to trainers when I was supposed to be working out and I’ve managed to pick up a few bits and bobs over the years.
One of the really interesting things is that muscles get used to particular types of exercise, to the point where they almost get “bored” and are only going through the motions. For instance, the classic chest press, something absolutely every guy at a gym is compelled to do (it’s something in the hormones, I swear), can become almost useless if done exactly the same way every time. Changing things up even a little, such as using dumbbells instead of a bar, changing the angle of the press, using a swiss ball instead of a bench, can make a really big difference and get the muscles firing up again.
I’m going to hazard a guess here and assume that you’ve gotten really good at your yoga moves, but that lately you haven’t been feeling the same sort of buzz. Partly that will be that it isn’t new and shiny anymore, but I’m guessing that another part is that your body is simply getting used to yoga.
Pilates is pretty close to yoga, close enough that you’ll probably feel pretty confident the first time you try it, but it’s got a different focus, more on building core strength and particular muscles. If you start interspersing pilates with your yoga, say a fifty-fifty split, you might find that your body is once again being challenged and that your yoga becomes interesting again.
Or you could get into something totally different, and really change things up. Boxing is one of my favourites (it’s a cardio workout that doesn’t get boring!) but that needs at least one other person, and most gyms offer it in a class, which is less than ideal for a number of reasons, not least of which is your social anxiety. Classes also suck because the instructor is never able to give proper one-on-one attention to address poor form or going at the wrong pace.
A good one might be high intensity interval training (HIIT), which involves, as the name suggests, short bursts of high intensity exercise designed to boost overall strength and aerobic fitness. Many of the routines are designed to be done without gym equipment, too, so you can do them at home or, I dunno, in a park or at the beach or wherever you might like to exercise.
The thing that I find helps with more intense aerobic exercise is dance music with a constant beat. Mid-nineties techno like the Chemical Brothers is ideal! But avoid dubstep at all costs - those sudden tempo changes are bloody awful when you’re trying to regulate your breathing.
Anyway, that’s my two bob’s worth. Have a crack at pilates for starters and see if that helps with the yoga.