We decided to do this trip a long time ago. Did we know what being on a train for many hours would be like? No, actually we took our first overnight train from Zürich to Berlin in march this year and it was not the best experience. I had a bad cold and people kept coming and going.
This time was different. Our longest train ride is our fourth overnight train on our trip. We had the old train, the new one and now we are on a train somewhere inbetween. First of all, I am a huge fan of having boiling hot drinking water available at all times. We can make tea, coffee, oatmeal and soup. We also brought some bread, cheese, cucumbers, apples and mors (mixed berry juice) on the train, so we have plenty to eat and drink. You can make yourself quiet comfortable on the train if you pack the right way. We put everything we might need during the train ride in our small bags and everything else we put underneath the lower bunk. We didn’t have to worry about getting to our stuff or unpacking/packing in the small 4 bed cabin. Since it is the end of september and it is not high season we were as lucky as having the cabin for ourselves for almost 24 hours straight. This was nice since you can move around more and can play the ukulele, talk and eat whenever you feel like it. What I also enjoyed were the longer stops where you can go outside, walk around and get some fresh air. The time can vary from about 20 to 50 minutes. 
Theses stops occur a couple times a day. Difficult to say at what times because on the train you are on Moscow time but the sun reminds you that you are going east. The city we are heading to (Irkutsk) is 5 hours ahead of Moscow. When you know you will be a long time on the train and have everything you need in your small bags, you can make yourself quiet comfortable.
We played the ukulele, read, did sudokus and crossword puzzels, followed up on my travel diary and I studied chinese with hello chinese, chinese skill (two really nice apps to study the language) and my notes from the class I took at the VHS Tempelhof-Schöneberg. This will hopefully be helpful during our china trip but it did not help me with conversations on this train. So we had to manage with words of russian, english and german as well as gestures and pointing at things. It worked very well but we could not get into the more complex issues of life. No groundbreaking communication but getting along and talking about travels, weather and food. We also got a little adventurous when we stopped for half an hour and women were selling their homemade pastries, smoked fish, homegrown vegetables and coocked potatoes with dill. We got ourselves some pastries (that were filled with mashed potatoes), a fish and a bag with tomatoes. Long story short the pastries were delicious.
Another occupation is staring out the window as we pass the siberian landscape. Small villages, big cities, fields, wild cotton, creeks, lakes, ponds and rivers, and many miles of birch tree forests, all wearing their colorful fall dresses, these are a few of my favourite things and they all pass by our window. At night it is manageble to see some stars but mostly you listen to the train on the railroad tracks until you slide into the land of dreams. 
On the second day on the train I started to miss our walking exercises ( we had been walking 10000 to over 30000 steps a day/everyday since sept. 14th), so I did a couple yoga excercises and at the longer stops some stretching and warm up moves I picked up at the Nike Run Club Berlin #NRC. That helped a lot. Now we are only a couple of hours away from our destination and I should try to sleep a little befor we hop of the train and make our way down to lake Baikal.