I've ridden a Trek Fuel EX 8 on the trails for the last three years, and right now I'm getting back into it. Coming back to something you used to do regularly is humbling in a useful way.
Start below where you left off
The temptation is to go straight back to the trails and the pace you remember. The smarter move is to start easier than your ego wants: shorter rides, trails you know, and enough left in the tank to want to come back. Consistency rebuilds more than one big ride ever will.
Check the machine before the rider
A bike that's been sitting deserves a once-over before it goes back on dirt: tire pressure, brakes, chain, and suspension. It's the same habit I have with the boat and the same one I have at work. Know the condition of your equipment before you depend on it.
Why trails
On a trail there's nothing to monitor and no notifications. The next root, rock, and turn take all of your attention, and that's the appeal. It's one of the few places where my brain fully switches off from work, and I come back clearer for it.
The point
Getting back into anything is a series of small rides, not one big one. Show up, keep it manageable, and let the momentum build.