When expressing vigorous support or agreement for something, you might use the phrase "were all for." However, there are many other ways of conveying similar sentiments. For example, you might say you are in favor of, enthusiastic about, or fully endorse a particular idea or action. If you want to emphasize your excitement or commitment, you could say you are all in on a particular plan or behind it one hundred percent. Other expressions that convey strong agreement or support include being on board with, fully behind, or wholeheartedly supporting something. Whatever phrase you use, the key is to communicate your unwavering backing for the idea or action in question.