I heard an explanation on that chazal- although tzadikim want to do a lot, they can’t be sure that they will physically be able to accomplish as much as they’d like. They say the minimum because their words are precious to them and they don’t want to go back on what they said. So they start with the min and end up doing the max.
Talking about ahavas yisroel and things like that is different, because it’s not a specific action. When we discuss it, it stays at the forefront of our mind and then we end up bit by bit accomplishing a lot until it becomes second nature.