As seems common in the thread, my motivations have evolved as time has gone on.
I was first licensed in 1997, I took my RAE (Radio Amateur’s Examination) before I knew much about ham radio. I was exposed to ham radio during my last few months at school, so I signed on to the full course as I began at college, in addition to my other studies.
I didn’t have a ham shack (and actually never have), so my only operating activities were out and about, and also at the radio club. I took my Morse test in 1999 after being helped to learn Morse by radio club members, so by February 1999, I was at the top tier with no idea! 
In 2001, I had been driving a car for a year or so, so I decided to go on a solo adventure to the isle of Mull for fun. The FT-817 had just launched in the UK, so I bought one for my trip. I had an awesome trip to Mull, it stands out as one of my best holidays, however I only managed one QSO on the radio!
In early 2004 I was operating my FT817 from a local high spot in the car when I worked Rod M3HLD on Pen Y Ghent G/NP-010 on 2m FM. Rod explained about SOTA and I immediately recognised that it would be a perfect activity for me - I even had the right radio!
I was hooked on SOTA straight away and started activating eagerly. Life then got busy; moving into my own home, girlfriend (later to become wife), a child, etc, all within a couple of years.
SOTA was a means to get on air and speak to people for me. I’d done a few mountains during school trips, but it has been SOTA that got me into hillwalking. Winter is a less busy time for me regarding family stuff, so I have concentrated on collecting winter bonus points to try to get my SOTA activator score up a bit. I finally got my Mountain Goat in 2017 after 13 years!
After my Goat, my next motivation was to gain what I termed ‘True Mountain Goat’, which is 1000 activator points without bonus points.
Along the way I got really interested in building my own gear, SOTA is a means to test my creations 
In recent times, my motivation for SOTA is just to get on air and connect with ‘friends’. Some friends I have met in real life, others I haven’t. The SOTA points are not too important to me these days although I would like to reach 2xMG.
73, Colin