Backed out of implies withdrawing or retracting from a commitment or promise. Antonyms for this phrase include committed, fulfilled, persevered, and completed. If someone "backed in to" a situation, they can be described as dedicated, responsible, reliable, loyal, and determined. If committing is not for them, they could be described as capricious, fickle, or impulsive. If they continued on their course, they could be called steadfast, resilient, or determined. In conclusion, while to back out of something is often seen as negative, there are many words to describe the opposite to suit different contexts and personalities, and it's always good to be aware of such words.