Full disclosure up front: I am not a mountain biker.
History: way back in 1994, I bought my first "real" mountain bike, a shiny new entry-level Trek Mountain Track 820. It was chromoly steel and heavy as hell. It had no suspension. It was very basic. However, I knew it was worlds better than any crap bike from Wal-Mart/etc, and it fit my ~ $400 budget. I proceeded to occasionally beat that bike like a rented mule, and it took everything in stride--numerous rides along Y mountain, countless trips to Mt Nebo, up Provo canyon, and even a few trips to Deer Creek resort. It even sent me to the hospital once due to a concussion from a crash, but that's a story for another day.
Then at the end of 1998, I bought my first Jeep. Suddenly, I wasn't riding my bike in the hills any more. I did use the bike on pavement, but only infrequently, and eventually its condition declined substantially. Once the problems got too numerous, I quit riding it at all.
Years passed. I kept telling myself I wanted a new bike--something I could actually ride, something I would want to ride. But still I did nothing. Finally, I decided to throw away the old thing. Surely that would motivate me to go buy a new bike, no? Well, that was years ago. So perhaps now you'll appreciate the significance of the following statement:
Last night, I bought a shiny new Trek Marlin 4.
Once again, this is Trek's entry-level mountain bike. Once again, it fit my ~$400 budget. But my, bike hardware has progressed over the last 26 years. Now I've got an aluminum frame, front suspension, 29" wheels, and disc brakes front and rear. Wow! This is so much better than my old bike.
Weather permitting, tonight after work I'll begin overcoming the inevitable saddle sores by doing some simple laps around my neighborhood.