The problem I have with ACT is that it's like the Intelligent Design of psychology. It takes clinically proven, scientific ideas (CBT) and ties them in with spiritual ideas (Budhism). If you ask me, I would say that the inventor of the approach just did this to sell and make money. He knew that most people used spirituality and religion to give them a sense of guidance and meaning to their lives, so he capitalized on this fact in order to sell these "new" ideas to a much larger audience.
Anxiety and depression are nothing more than bad habits of insecurity that you pick up. There are obvious genetic predispositions, but that doesn't mean you have to be a slave to your mind for the rest of your life. It means that the person has a lower threshold for susceptibility. That's all. If you have a habit of smoking, what are you going to do, tell yourself it's ok, become one with your habit, and then continue to fill your lungs with harmful cigarette smoke hoping that you quit? No, you're going to starve the habit until the feelings to smoke go away. That's how I view anxiety and depression, that's what seems logical, and that's what has worked for me and many of my friends.
But you have to realize that those "distracting thoughts" aren't natural and shouldn't exist to begin with. The problem is that us humans have this unnatural need to control life due to our advanced consciousness. Think about this: does an alphamale gorilla get depressed if his penis was a little smaller than some of the other male gorillas in the wild? Hell no. That beast has one natural directive, and it's to mate with as many female gorillas as he can. Does a lioness sit on a tree for weeks and sulk if a lion messes with the pride and kills her cubs? Heck no, she's spraying pheromones like a firehose the next day. Can a shark turn into the Jigsaw killer and plan out a bunch of psychological murder schemes with his prey? Nope, it only knows one thing: acquire & kill.
Depression and anxiety (including social anxiety), in my opinion, is nothing more than a habit that you generate from unnatural control thoughts spun by our little advanced brains, or insecurity-driven thoughts. We start developing strategies for control at early ages; some of us worried a lot (or tried to keep in control by trying to predict what was around the corner in order to prepare for it), some of us were shy and avoidant (or tried to keep in control by avoiding the chaos of being put on the spot and not knowing what to do or say), some of us were hostile (or tried to keep in control by pushing people away - by pushing away, they couldn't hurt you), some us were perfectionists (or tried to keep in control by avoiding messing up), etc. Over time, these control strategies became habituated and became a part of us. We were like jugglers juggling balls of worry, doubts, fears, ruminations, negatives, etc. And then one day, one of the balls fell. And then another fell. And another. Before we knew it, the symptoms crept up on us, and we became depressed or anxious. Up until that point though, we felt like we were in control of life.
In other words, insecurity and uncertainty generated fear, the fear was countered by an attempt to control life with an array of unnatural control strategies, and finally, the effort it took for you to control life eventually wore you down as the symptoms of depression oranxiety then crept in. Congratulations, your unhealthy, unnatural thought pattern has just generated depression.
The ultimate goal of an unhappy or anxious person is to build enough self-trust to live a reactive, spontaneous life (a life akin to an animal in the wild); a life that doesn't dwell on unreasonable thoughts of the past or worries of the future; a life that's completely in the moment. What anti-depressants do is shrink the habituated control/insecurity thoughts, the only problem is that all the other side-effects usually cause more stress, and thus more depression and loss of hope. It's a vicious cycle for some people who take meds.
That's what seems logical, especially when you read that our DNA is 99% similar to that of a chimpanzee. All the "mindfulness"and "ACT" crap makes absolutely zero sense at all. The only reason some people find that it works is the same reason people going to church believe that they're more humble and peaceful than everyone else: the ideas give you a false sense of meaning, guidance, and security. It doesn't work at the core or root of the problem.