SQL Server Service's Log On As account

I just inherited a set of new servers and whoever set them up left the "Log On As" account as the default "NT Service\MSSQLSERVER". I'd like to change that over to an Active Directory service name. I have never attempted changing it after we have already went live in production. Is there anything I should be aware of? Will it require a restart of the service? This server is only using SQL, not SSIS, SSAS, SSRS. I will make sure the AD service name has access to all the folders necessary to reach files. Anything else I'm missing?