I meant, if in the same situation, a pessimistic will just think of the bad thing, meanwhile the realistic one will consider every possibility. You can combine optimistism and realism to create a motivation to move on and the strength to accept things would happen in any way. Once you have learnt to accept, pessimistism isn't a real matter anymore because you'll manage to categorize the results into bad and good, depending on how you want your mood to be. In other words, once you have learnt the acception, you have also learnt to decide what feeling you want to feel to take over the immediate ones the situation might bring to you.