Wanted to trek the Inka Trail for years. And have finally done it (for my partner's 40th birthday)!! . Hadn't really expected it to be so challenging. Fell ill at the beginning of day one and was convinced I would have to turn back. But, my partner and our guide stuck with me and we made it through.
The ascent to Dead Woman's Pass almost killed me, but was totally worth it when I'd finally crawled up to the top. The views are incredible. Day 3 was beautiful and lush with vegetation.
Day 4, the climax! Well, Machu Picchu is AMAZING and just speaks for itself.
I totally recommend this trek to anyone with a sense of adventure (with a decent level of fitness and without a heart condition).