How can I be optimistic about my job?

Try to find the positive points about your job and find ways to motivate yourself.  If you still feel this isn't helping you, then take the time to analyse your interests, goals and reason for working.  Once you figure it out, channelise your energy to finding a suitable job according to it. 

You will see it will work wonders.   In the present, maybe you are bored about it, which is why you are looking for ways to be optimistic about your job.