for the long haul

for the long haul (for a long time, permanently; for a long period of time; over the long term; until the end, until it is finished; without hesitation, without reservation) — надолго; всерьез и надолго; до конца; не бросая начатое

long haul (a long period of time (during which work continues or something is done); a lengthy job) — большой срок, то, что рассчитано на долгорочную перспективу

Example 1: If you’re going to college, you have to be in it for the long haul. You can’t quit. You have to stick with it until you graduate. (EB)

Example 2: Cliff says he’s in this relationship for the long haul, but I can tell that he’s getting bored. He always looks at other girls. I really don’t think he loves me anymore. (EB)

Example 3: Before you invest in Internet stocks, be sure you can afford to invest for the long haul. (thefreedictionary.com)

Example 4: He has decided to stay here for the long haul and will not return to his home country for awhile.

Also used in the form
over/in the long haul (during a long period of time)

Example: It's possible, over the long haul, to see changes in the populations of these birds. (thefreedictionary.com)

Opp:
over/in the short haul/run (over a short period of time)

Example: The business plan looks unprofitable but only in the short haul.

Related vocabulary:
[go the distance]
[play for keeps]
in the long run