I was able to unlock this about a week after starting the game with a mix between some fairly active playing and idle time of only checking in once or twice a day. Basically, you will want to go as high an area as you can before it slows down. When you reset, this will increase your favor for the deity of the current campaign you are in.
This favor relates to gold find which will allow you accumulate more gold by the time you reach the same level the next time, thus pushing a little farther. You will have to repeat this many times to increase the areas until you reach 100. Eventually you will have to find the balance between keeping favor for gold find and putting it into blessings which increase other stats.
It is usually easier to push farther during events. You are able to accumulate more favor and the monsters are a little easier. Also, you may want to take advantage of any weekend buffs if you are having trouble with a certain boss stage.