I've once or twice had a similar experience but for me it's not lasted more than five or ten minutes. The onset when it has happened has been astonishing. Thoughts just come to a stop, and whatever I was about to think about, it seems like it can wait until later.
When I look at what prevents this happening more often, it's a couple of things. One is that I suffer from a belief that if I'm thinking about something, it must be important and I'd better be careful not to forget it, so I need to continue thinking about it. Another is a belief that thinking will protect me from harm, because thinking is (allegedly) a good way to anticipate and avoid potential problems. But that's not really borne out by experience: thinking, at least of the gadfly variety, is far more likely to distract me from things of real importance.
I was thinking about Scott Kiloby's exercise of resting in awareness, and thinking that it's a nice way to have this thought-free experience for a few seconds. In those seconds, there is an absence of the usual sorts of suffering that one experiences on a daily basis. One is not concerned about the future of one's career or relationship or health. One does not suffer self-esteem issues or painful memories of childhood or family interactions. One simply experiences what is present in the moment in a peaceful way. And thoughts are conspicuous by their absence.
Having had the experience of thoughtlessness and found it quite pleasant. I'm interested in recapturing it, and I wonder if it might be possible to remain in the resting-in-awareness exercise for a minute, and later an hour, and later an entire day, and eventually all the time. When I try to do this, what comes up to hinder my attempt?
I usually start with my eyes closed, and it's simply not practical to go through my day with my eyes closed. But I can continue with the eyes open, focusing on body sensations like breathing or warmth to avoid getting too engaged in thoughts. Next comes the fear that without thoughts, I will lack ambition, and without ambition, I won't accomplish anything. Rationally I know that my thoughts often get in the way of ambitions more than helping with them. And I know I'll run into the belief that thinking is necessary for safety, and again rationally I know that's not the case. I think this is something to continue tinkering with, and see if I can get anywhere with it.