Bias limits our understanding of the world because it presents a fixed framework for experiencing certain people, places, things, or ideas. Bias does not always necessitate prejudice, as some people may have only had a pattern of experience which developed and reinforced the bias. For example, if someone felt that broccoli was a disgusting vegetable, but they had only ever had it cooked in such a way that it tasted bad, they would be said to have developed a bias against eating broccoli. This wasn't the person's fault, though! They've never had any experiences which open them to the possibility that broccoli can taste good when cooked well.
With that, it is primarily the responsibility of the individual to challenge his or her own biases. It takes some amount of bravery, sympathy, and willingness to consider new information to confront the biases we hold. Let's return to the example of a person who has only ever had poorly-cooked broccoli. They might be shutting themselves off from hundreds of broccoli dishes which taste great! If this person feels especially brave (or has the support of others), they may be willing to try something new, even if they haven't eaten broccoli in years.
I think that sympathy comes more in to play when we must confront biases we hold about other people or ideas. For example, I personally felt for a long time that people who played sports were rude, because I had many experiences where people who played sports happened to be rude to me. When I opened myself up to thinking sympathetically, I realized they were probably not wishing to attack me personally, and were more likely trying to distance themselves from something I represented to them.
We often hold biases without realizing it or fully comprehending the ways they limit our lives. Through consistent self-examination, we can open ourselves up to challenging and removing bias. By challenging our biases and having positive experiences which outweigh any negative reinforcing ones, we can have a more objective perspective in life. Similarly, having a number of negative experiences with something to which we were positively biased can help to ground us in reality.