Lemme weave you guys a tale.
I was born a decade and nine years ago on December 26th of 1999. About 2 hours shy of getting presents cheated out of me. My earliest memories of trains take me back to 2002 and 2006. In 2002 I was given my first ever actual train set by my mom, a Tomy Thomas & Friends "Giant" Train set. Unbeknownst to her, she introduced me into a hobby that will last until the day I kick the bucket. In 2006, I got two separate train sets on two different occasions. The first was a Bachmann N-Scale Santa Fe "Explorer" Set, a tooth fairy present (to this day I still wonder why the box shows a UP Boxcar whereas mine came with a GB&W Boxcar). The other was the Lionel #31960 Polar Express on Christmas Day, the real start to my O-Gauge collection. My Uncle got me the Polar Express, and in frequent occasions still throws in a boxcar or two on Christmas day every year.
I started growing and growing the collection of Thomas and Lionel but once I became the dreaded pre-teen (like most of you guys), they all went into the boxes and storage bins. Even the Polar Express saw limited use under the tree. I started finding interests in other things, such as those mystical creatures we call girls, video games and other forms of toys. The big chugging steamer became "old news" and I was the only child in most of my classes who still had an interest in trains. Even during my pre-teen years, my uncle still gave me some cars (George Washington Boxcar is one I remember) but they remained "collectors" items and stayed in the box.
Middle school was very rough for me. I trekked through differing forms of bullying, hard assignments and it just devastated me. One time during a break, I was in one of those complete and utter boredom situations. TV didn't suffice, all the games I've played, reading was OUT of the option, I didn't have anything to do. Tucked away in the corner of my room was my Lionel Pennsylvania Flyer set (SKU #30018), and I decided I might as well run it for a bit just to cure my boredom.
Running that train suddenly reminded me of my younger years once more. It took me to a time when I didn't give a care about anything. Issues in the world, gone. Bad day at school, gone. Boredom? OUT the window! Over the course of 2014 I have managed to amass an impressive collection of Lionel and three "oddballs" in my O-Gauge roster. Everything grew to its current, and growing, size of 8 sets, 2 separate sale engines, and 69 pieces of rolling stock. All together, this totals up to about 108 individual items. Even Thomas, who unfortunately still lives in the storage bin, gets occasional use when I have younger cousins come over. I also recently bought my first Thomas item in ages, a Troublesome Van (Growing up I never had one of these cars. Now I do!).
I don't use the Thomas or my N-Gauge stuff as much anymore, but every now and then I still yearn to take them out and remind myself of the days when I yearned of making a big layout on a door. Same thing applies for Thomas, although the layouts kinda became reality as I had plenty of track and engines at my disposal. Only limit was when my family started complaining about accidentally knocking over stuff ^^; Whenever my cousins come over, layouts are made but they will never be as grand as they once were.
Right now my "Layout" is currently the room of my floor and the living room when Christmas rolls around. Our garage has been the subject of debate for a possible layout but I've accepted the fact that it is not going to happen because we have too much stuff stored. The attic is too unstable and we do not have a basement. Doesn't bother me, I like the floor layouts. NOTHING beats dropping to the ground and seeing the little engines whiz by. 
I plan to pass this stuff down to my children one day and let them experience the same emotions and feelings I did.
