The natural numbers (positive integers) are the numbers 1, 2, 3 , 4, 5, .... The "..." signifies that there are infinitely many such numbers, so there is no la

The natural numbers (positive integers) are the numbers 1, 2, 3 , 4, 5, .... The "..." signifies that there are infinitely many such numbers, so there is no largest natural number but there is a smallest (1 is smallest). In that sense it is infinite in only one direction - written here it is infinite to the right but has an end at the left. Nothing special happens as you "approach infinity" and in fact that's not a thing you can do. No matter how high you count, you have only have counted finitely many numbers and there are an infinite set more that you have not counted.