1

Win the heart of a certain person

A deep-seated desire to be loved

It's all a big misunderstanding

2

Discover the true identity of an important person

A pathological need to be appreciated or admired

A rival is interested in the same thing

3

Return to their homeland

A genuine sense of concern for others

Doing so would anger a local politician

4

Slay a powerful monster

A promise to a dying family member or friend

It's really, really far

5

Defend a group or settlement from an impending attack

Spite, plain and simple

Some else has done it already, but they did it wrong

6

Discover the location of a fabled natural feature

A hunger for power

They're unknowingly missing a key piece of information

7

Destroy a powerful magical artifact

A quest of self-improvment

A location involved is very dangerous for this character specifically

8

Obtain a powerful magical artifact

The search for spiritual enlightenment

They have sworn a vow that makes it much harder to do

9

Find and recover a kidnappe dor missing friend or family member

Everyone else was doing it

There is a rebellious prohibition against doing so

10

Claim an ancestral birthright or fortune

It just seemed like fun

An injury prevents them from doing so

11

Defend or mentor an important young person

A prophecy says they will and they believe it

A person integral to doing so is hostile to them

12

Prove the existence of a certain phenomenon or being that is thought to be fictional

The pay was too good to turn them down

A persistent misconception means they are mistaken

13

Forge a peace or alliance between two groups

The pay was too good to turn down

Two other groups are involved in the same goal

14

Conceal a secret by destroying evidence or a person

Revenge

The trail has gone cold

15

Interrupt a ritual or spell that would cause a grand negative effect

Prove themselves worthy of a love interest who does not return their feelings

A classic switcheroo has confused similar people or items

16

Destroy or neutralize a certain powerful person

Restore their family's good name

Two factions or people who do not get along must cooperate to make this happen

17

Reconnect with an important person they used to be close with

Get the attention of a potential patron

An important person or object is accidentally destroyed before much progress is made

18

Discover their true identity

An inexplicable compulsion that's probably related to childhood somehow

Doing so would break an important treaty

19

Learn important knowledge that has been concealed or locked away

Gain experience in a skill needed for another task

It has literally never been done before

20

Kill a god

God told them to

Religious zealots, proficient in fighting, stand in the way