public function setup_nav( $main_nav = array(), $sub_nav = array() ) {

		// Stop if there is no user displayed or logged in.
		if ( ! is_user_logged_in() && ! bp_displayed_user_id() ) {
			return;
		}

		// Determine user to use.
		if ( bp_displayed_user_domain() ) {
			$user_domain = bp_displayed_user_domain();
		} elseif ( bp_loggedin_user_domain() ) {
			$user_domain = bp_loggedin_user_domain();
		} else {
			return;
		}

		$slug          = bp_get_activity_slug();
		$activity_link = trailingslashit( $user_domain . $slug );

		// Add 'Activity' to the main navigation.
		$main_nav = array(
			'name'                => _x( 'Activity', 'Profile activity screen nav', 'buddypress' ),
			'slug'                => $slug,
			'position'            => 10,
			'screen_function'     => 'bp_activity_screen_my_activity',
			'default_subnav_slug' => 'just-me',
			'item_css_id'         => $this->id
		);

		// Add the subnav items to the activity nav item if we are using a theme that supports this.
		$sub_nav[] = array(
			'name'            => _x( 'Personal', 'Profile activity screen sub nav', 'buddypress' ),
			'slug'            => 'just-me',
			'parent_url'      => $activity_link,
			'parent_slug'     => $slug,
			'screen_function' => 'bp_activity_screen_my_activity',
			'position'        => 10
		);

		// Check @mentions.
		if ( bp_activity_do_mentions() ) {
			$sub_nav[] = array(
				'name'            => _x( 'Mentions', 'Profile activity screen sub nav', 'buddypress' ),
				'slug'            => 'mentions',
				'parent_url'      => $activity_link,
				'parent_slug'     => $slug,
				'screen_function' => 'bp_activity_screen_mentions',
				'position'        => 20,
				'item_css_id'     => 'activity-mentions'
			);
		}

		// Favorite activity items.
		if ( bp_activity_can_favorite() ) {
			$sub_nav[] = array(
				'name'            => _x( 'Favorites', 'Profile activity screen sub nav', 'buddypress' ),
				'slug'            => 'favorites',
				'parent_url'      => $activity_link,
				'parent_slug'     => $slug,
				'screen_function' => 'bp_activity_screen_favorites',
				'position'        => 30,
				'item_css_id'     => 'activity-favs'
			);
		}

		// Additional menu if friends is active.
		if ( bp_is_active( 'friends' ) ) {
			$sub_nav[] = array(
				'name'            => _x( 'Friends', 'Profile activity screen sub nav', 'buddypress' ),
				'slug'            => bp_get_friends_slug(),
				'parent_url'      => $activity_link,
				'parent_slug'     => $slug,
				'screen_function' => 'bp_activity_screen_friends',
				'position'        => 40,
				'item_css_id'     => 'activity-friends'
			) ;
		}

		// Additional menu if groups is active.
		if ( bp_is_active( 'groups' ) ) {
			$sub_nav[] = array(
				'name'            => _x( 'Groups', 'Profile activity screen sub nav', 'buddypress' ),
				'slug'            => bp_get_groups_slug(),
				'parent_url'      => $activity_link,
				'parent_slug'     => $slug,
				'screen_function' => 'bp_activity_screen_groups',
				'position'        => 50,
				'item_css_id'     => 'activity-groups'
			);
		}

		parent::setup_nav( $main_nav, $sub_nav );
	}