Maddie
I am a very nervous flyer and have been since my days in the military. The flight crew are really reassuring when they state quite correctly that you are safe. That is a rational view. However, flight anxiety has some irrational elements to it. The crew can be trusted to get on with the flight and to get you to your destination safely. I have no fear of the aircraft crashing, or turbulence, what I fear is within my own mind.
If it helps, the nervousness is not always a product of rational thought, its a subconscious reaction. It can't be thoroughly controlled by rational thought as the effects can be biological, such as adrenaline release. This can do some odd things to you. You can sometimes recognise the triggers for anxiety and learn to deal with them, such as the take off acceleration. I usually count. One per second. Thousand and one, thousand and two etc. Its a simple thought process and has a progression about it. You just count from one number to the next. Its also finite in that each flight has an estimated arrival time and its possible, although tiring, to count each second. Eventually the anxiety subsides and you miss numbers, for me about 5 minutes after take off. You can then convert the time counting into the length of songs on an ipod, (just 20 songs until we land) or 2 more movies or TV shows. That is the sign that you have successfully controlled the fear.
I have loved ones in the south of Russia, and its usually a three flight journey there. I cant say I enjoy the trip but I can do it. Feel the fear and do it anyway.