Edit the web.config of the Sitefinity site, for which you want health checks to run and add the new entry in the appSettings section with the following line:

<add key="sf:HealthCheckApiEndpoint" value="restapi/sc/healthcheck" />

Next you must enable and configure the health check service by following these steps:

1. Navigate to Administration > Settings > Advanced > System > Health check service
2. Select the Enable Health check service checkbox.
3. Select the Enable logging of health check tasks checkbox. (All request, response, message and timestamp is stored in the healthcheck.log file, located in the ~/App_Data/Sitefinity/Logs folder )

For more information, please see the Sitefinity CMS Health Check service documentation.