If you hold a glass of water at arm's length, for the first 5 or 10 minutes it's ok, you can manage. After half an hour your arm begins to ache and you want to put it down. After an hour it becomes really unmanageable. That gives you an idea of stress. If you hand the glass to someone else to hold, then you share the stress. So in your situation, it's better to share it with someone before the stress takes effect. Poor EMS, maybe you should have shared it sooner!