The phrase "start an activity" is correct and usable in written English.
You can use it to refer to a general activity, or any specific activity. For example, you could say "Let's start the activity now" or "We need to start an activity to get the children engaged."
It usually goes something like this: You start an activity and develop a love for it, so you do it more often.
Today we're going to start an activity that puts each one of you in the role of White House adviser, assigned with researching and giving advice to the president on how to deal with the crisis.
You never have to launch the app to start an activity, it just works.
With this version of OS X, Apple now lets users start an activity on their Mac, and then pick it up on their iPhone or iPad, or vice versa.
But we also may ask ourselves to definitively stop or start an activity we either want to jettison or introduce into our lives, as in start an MBA, stop procrastinating, start meditating, stop using condoms (aka have a baby).
The sample consisted of middle-aged women who were just starting an activity program after having remained sedentary for at least 1 year prior to participation.
In the last 2 years GVT also started an activity related to the production of FLiBe for fusion application and, as beryllium dusts and fumes are hazardous materials special safety equipment have been developed.
Moreover, the device stays in PSM until it starts an activity such as UL data transmission.
It seemed completely wasteful not to have a common format, so I started an activity within the Molecular Graphics Society [6] to systematize file types.
when starting an activity; when wanting to find out information from others.
