For me it started when I was about four years old, seeing the movie 'Moby Dick' at our local Summer film theater for kids. At the age of five, my parents took me to Mystic Seaport, and the New Bedford Whaling Museum (they have a 1/2 scale whaling ship, that is perfectly full scale if you happen to be just about 3' tall!). I had my first 'real' boat by the age of six, that I could paddle about in the local pond (and I rigged it about four different ways in order to get it to sail...but not very well!). At the age of eleven, I taught myself to sail properly at the Community Yacht Club in Boston, which cost $1 per season to be a member, and you could use all of their boats on the Charles River (Cape Cod Mercurys, Finns and 420's). I talked my way into a scholarship at Tabor Academy when I was 14, sailed on their 420 racing team, and crewed on two different schooners ('Tabor Boy,' and 'Serendipity'), sailing from Booth Bay Maine to Bermuda, all over Buzzard's Bay, Martha's Vineyard and Nantucket, and then went off to college in Wyoming (of all places!). I missed the sea a lot out there, and started to build ship models seriously at that time (I had slapped together a number of ship models before then, but was more interested in WW1 aircraft until I went West). After I joined the Army, I managed to mostly get myself stationed near the ocean or lakes, continuing to sail in Chiemsee in Germany, Monterey in California, and finally ended up in the UK, where I bought my first proper boat, a 16' gaff cutter with a small cabin. I joined the Old Gaffers Association, and sailed and raced with the old salts on the Essex and Suffolk coasts of the UK (real 'Arthur Ransome' country!), eventually getting a larger gaff cutter (24') for offshore work. After I got out of the Army, I moved back to the States (Rhode Island), where I set up a yacht brokerage (specializing in classic sailing yachts), bought myself a house on the water and a 40' ketch, and continue to sail to this day.
Obviously, with all that time on the water and being in and around boats, boatyards, ships, museums, etc, etc, I kept building ship models, partly as a way of connecting with other times, other traditions, as well as the historical aspects of ship design, maritime history, and the craft of seamanship, but also as a way of figuring out how and why ship designers built their ships the way they did (and do!). A lot can be learned from a set of plans, but I find I get a lot more out of handling a ship model. Must be something about the '3D' and tactile experience really gives me a lot of insight into what the designer was trying to accomplish within the specifications he was given....