How to refactor methods like this one?

activity_status.rb

def activity_status
  if currently_working?
    'working'
  elsif worked_recently?
    'active'
  elsif has_activity?
    'inactive'
  elsif signed_in_at_least_once?
    'no_activity'
  else
    'never_sign_in'
  end
end

def activity_status
  case true
  when currently_working?
    'working'
  when worked_recently?
    'active'
  when has_activity?
    'inactive'
  when signed_in_at_least_once?
    'no_activity'
  else
    'never_sign_in'
  end
end

@kossnocorp,

def activity_status
  return 'working'      if currently_working?
  return 'active'       if worked_recently?
  return 'inactive'     if has_activity?
  return 'no_activity'  if signed_in_at_least_once?
  'never_sign_in'
end

def activity_status
  case 
  when currently_working?       then 'working'
  when worked_recently?         then 'active'
  when has_activity?            then 'inactive'
  when signed_in_at_least_once? then 'no_activity'
  else 'never_sign_in'
  end
end

Although above solutions are good, however i add new style for variability:

def activity_status
  currently_working? && 'working' or
  worked_recently? && 'active' or 
  has_activity? && 'inactive' or
  signed_in_at_least_once? &&'no_activity' or
  'never_sign_in'
end