MySQL After Upadte

I have written a trigger (with help from EE)

CREATE DEFINER=`root`@`%` TRIGGER trg_WalletIssue
    AFTER UPDATE ON tblpermit
    FOR EACH ROW 
	BEGIN
	IF New.CostWallet > 1 Then
    INSERT INTO tblservice_log
	
    SET      	DDAI_ServicesID = '4',
			id = New.id,
			UserID = (SELECT b.UserID FROM tblBatch b WHERE b.BatchID = New.PermitBatchID LIMIT 1),
			DDAI_Services_Date = NOW();
	END IF;
END

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My problem is that if any part of the record is updated the trigger will execute, this is causing multiple records to be inserted into the service log.

How can I only execute the trigger only if the CostWallet changes and is >1