❔ Making an async method without anything to async inside

let's say i have following scenario:

void Foo()
{
  for(int i = 0 ; i < 10000000 ;i++){} // simulate load
}

void Foo()
{
  for(int i = 0 ; i < 10000000 ;i++){} // simulate load
}

the following method is blocking, but also don't have anything that can await inside.
how can i turn this example into

async Task Foo()

async Task Foo()

❔ Making an async method without anything to async inside - C#