Commentary on Meditations: B9:3

Do not despise death: welcome it, rather, as one further part of nature's will. Our very dissolution is just like all the other natural processes which life's seasons bring - like youth and old age, growth and maturity, development of teeth and beard and grey hair, insemination, pregnancy, and childbirth. In the educated attitude to death, then, there is nothing superficial or demanding or disdainful: simply awaiting it as one of the functions of nature. And just as you may now be waiting for the child your wife carries to come out of the womb, so you should look forward to the time when your soul will slip this bodily sheath.

If you want another criterion - unscientific but emotionally effective - you will find it quite easy to face death if you stop to consider the business you will be leaving and the sort of characters which will no longer contaminate your soul. You must not of course take offence at them, rather care for them and tolerate them kindly: but still remember that the deliverance death brings is not deliverance from the like-minded. This alone, if anything could, might pull you back and hold you to life - if you were allowed to live in the company of people who share your principles. But as things are you see how wearisome it is to live out of tune with your fellows, so that you say: 'Come quickly, death, or I too may forget myself.'

Another passage, and reminder, on death.  Marcus uses the discipline of assent to break apart the concept of death.  Humans have feared and built up the fear of death so much, that many simply fear it without fully realizing what it is they fear.  When broken down and analyzed, there is nothing to fear in death.  It is a part of nature and is as natural as the changing seasons.  Marcus goes so far as to say that we should wait on our death as we would the delivery of a baby.

And if that doesn't quite help overcome the fear, then Marcus gives a few more reasons as to why you should welcome death.  You'll no longer need to deal with people that "contaminate" your soul.  Of course the opposite could have other effect - if you live among like-minded people, then you may want to hold on to life longer than death intends, in which case you fear death.  But the reality was, at least for Marcus, he was ready to part company of people who contaminated his soul.

Epictetus had a good analogy on the topic of death.  Death is like the captain of a boat.  You make port, leave the boat and go to collect water, food, trinkets, etc.  But all the time, you are mindful of the captain's call.  When he calls, you need to hurry as quickly as possible to get back to the boat and get on.  But while you're on land, that anticipation and waiting for the captain to call is analogous to waiting for death (see Enchiridion, passage 7)

(see also Citadel p. 270-271, 292-293, 296)