Our speaker is not going to let a little personal rejection get him down. He's showing a good model of what perseverance is all about.
Here is realization; Here is a man tallied—he realizes here what he has in him; (86-87)
These lines suggest that the experience of traveling the open road is no vacation. Instead, it's perhaps a true test of character, revealing just what you're made out of. Which version of the open road rings more true to you: ultimate vacay, or character-revealing test of will?
The earth is rude, silent, incomprehensible at first—Nature is rude and incomprehensible at first; Be not discouraged—keep on—there are divine things, well envelop'd; I swear to you there are divine things more beautiful than words can tell. (118-120)
The speaker wants us to know that life is not all high-fives and puppy dog tails out here on the open road. Nature can be a cruel mistress, and you'll have to contend with her in your travels. Persevering through those challenges is totally worth it, though—at least in our speaker's view.
Allons! we must not stop here! However sweet these laid-up stores—however convenient this dwelling, we cannot remain here; However shelter'd this port, and however calm these waters, we must not anchor here; (120-122)
Travel means discomfort—anyone who's ever flown coach can tell you that. At the same time, the speaker is encouraging his readers here not to quit moving, no matter how comfy the environs might get. The hardships of the road are worth persevering in order to enjoy the freedom and community that travel affords.
He traveling with me needs the best blood, thews, endurance; None may come to the trial, till he or she bring courage and health. (134-135)
You want to roll with our speaker? You better bring your A-game then. Apparently he's not taking a luxury liner to see the world. He's going to endure hard, physical challenges that must be overcome to keep you traveling on the open road.
Listen! I will be honest with you; I do not offer the old smooth prizes, but offer rough new prizes; (141-142)
"Rough new prizes" sounds like something they might give away on a really bad game show. All the same, that's all the speaker can offer you if you choose to travel the open road with him. He's not sugar-coating it here. To enjoy the character-building benefits of travel, you're going to have to do your fair share of persevering.
It is provided in the essence of things, that from any fruition of success, no matter what, shall come forth something to make a greater struggle necessary. (216-217)
With these lines, the speaker reminds us that struggle is a part of daily life. There will always be challenges to overcome, and when you overcome them, new challenges will arise, which you'll need to persevere through.