How do I remove the timeout in the boot menu

I installed several operating systems on my computer in a multiboot configuration (Ubuntu, Linux Mint, Windows, ...). When I turn on my PC, the boot menu appears with a timeout. Sometimes, I don't focus on it (I turn on my PC and then I go to the fridge to get a soft drink, for example) so that I miss the boot menu so I cannot chose my desired OS. Because of that, I must restart my computer and choose my desired OS again. Is there anyway to remove the timeout. I mean when the boot menu appear, so that there is no timeout, no OS will boot until I chose my desired OS. I am using Ubuntu and Linux Mint.