You can increment by any amount using i += step. This skips values instead of visiting every integer in the range. Example: for (int i = 0; i < 10; i += 2) prints 0, 2, 4, 6, 8. Only even numbers appear because the loop skips by 2 each iteration.
Custom steps work for counting down too: for (int i = 10; i > 0; i -= 3) prints 10, 7, 4, 1. You skip by 3 each time, stopping when i becomes 0 or negative.