I have been around monks and spent extended stretches of time at Orthodox Christian monasteries, and I'd like to clarify a couple of things: monks can and do get distracted and they can, indeed, just leave their cell and go outside if they want to. There is a passion called "acedia" that attacks every monk to a greater or lesser degree. Acedia is the "spirit of noonday". It's distraction. It's the desire to do anything else except whatever it is you're doing (especially prayer). It's the desire to be somewhere else or to do something else. It can take the form of gluttony, or the form of going to talk to another monk, or the form of just going for a walk instead of praying.

Also, monks are praying the whole time. All the time. They are usually repeating a short prayer in their minds while they work, while they walk, while they eat. All the time. Of course, they get distracted and their minds wander (especially the newer monks), but the aspiration is to "pray continually". They aren't just letting their minds wander around and think about whatever they want. A lot of their effort and attention goes into constantly guarding their minds against distracting thoughts and re-focusing on prayer.

Monks (Orthodox Christian monks, anyway) do, indeed, have freedom to choose something else, but the whole point of their ascetic struggle is to ignore those impulses and to stay in prayer.

I experienced one of those strict Vipassana retreat for 10 days where most of the distraction you take for granted in today's life are forbidden: no reading, no talking, no phone, no internet, no physical contact in the premises and no contact from people outside. It's the closest it can be to a life's monk. Your day is clearly structured, essentially waking up at 4am, meditating, doing some simple tasks, meditating, eating, meditating, eating, meditating, sleeping. If you play the game (which I did), you literally spend 10h/day meditating. In a sense "boredom" just becomes an experience by itself which paradoxically isn't boring anymore.

As it's been noticed here, surely monks were not distracted by the same technology and at the same scale we are distracted to in today's world. When I came back to the "real world" from this experience, I could realise how much one life's was just constantly distracted.