"a healthy activity" is a correct and usable phrase in written English.
You can use it anytime you want to refer to an activity that is good for health. For example, "Jogging is a healthy activity that I do every morning."
At the same time, in communities where drugs and alcohol have wreaked havoc, poker can seem like a healthy activity.
Some dedicated soccer fans say that the violence is tarring what had been a healthy activity.
Cycling is a healthy activity and cyclists live longer on average than non-cyclists".
Zhang Jianrong, a woman who was nearly six feet tall, told me that basketball was just a healthy activity for her daughter; the girl's studies were more important.
The Pentagon's survey of attitudes about gays and lesbians serving openly was an exercise in self-examination — a healthy activity.
She said she was trying to avoid belting — not a healthy activity for an opera singer's vocal cords.
Its message was that nursing a 3-year-old was outrageous and inappropriate, when in fact nursing a 3-year-old is a normal, healthy activity in the world today".
Even if it's clearly not a physically healthy activity, maybe smoking provides some sort of mental health benefits, especially for those of us who do it to relieve personal stress.
Medical experts consider masturbation a normal, healthy activity as long as it is not causing stress in your relationship.[11].[11]
Commuting by bicycle is generally a safe and healthy activity, but collisions are always a possibility.
There may be an opportunity here for Headspace — and Hoffman — if the company is able to convince large businesses that meditation can be a helpful and healthy activity for their employees.
