Grant permissions to a role rather than a user and then assign users to the role. A user is more likely to leave than a role is to become obsolete.
USE MyDatabase
GO
DECLARE @sProcName SysName
SET @sProcName = ''
WHILE @sProcName IS NOT NULL
BEGIN
SELECT @sProcName = MIN(Name)
FROM SysObjects
WHERE Type='P' AND
Name > @sProcName AND
Name LIKE 'usp%'
PRINT @sProcName
IF @sProcName IS NOT NULL
EXEC('GRANT EXEC ON ' + @sProcName + ' TO MYROLE')
END