In reply to Greasy Prusiks:
I'm very goal oriented and extremely familiar with that sense of deflation you describe. It usually arrives for me shortly before the goal is reached, when the final moment looms close instead of the far-fetched ambition it once seemed.
Chasing Wainwrights taught me this lesson in my teens and early 20s. I recall what a huge challenge climbing 214 peaks appeared to a 14 year old in south London catching the coach up to the Lakes. As I neared my goal 10 years later it dawned on me how underwhelming it felt to secure that final summit.
It strikes me as very unimaginative to repeat the same goals. I've never wanted to compleat the Munros or Alpine 4,000s. As others have pointed out, it's the journey that matters. The good old Lakeland fells were the right challenge at the right age and since then I've had other big challenges and continue to set new ambitions.
Building a business, raising a family, landscaping a nature reserve, the experience has been the same. At once both intimidated and inspired by the scale of the challenge. At the end, deflated and seeking the next objective.
And yes, a rest is essential. I think it's important that your next dream comes to you over time. Don't rush into something that is just the old challenge in new clothes.