Agile software development approaches have gained interest by leveraging goals such as small initial investment, incremental development, and rapid feedback. In contrast, application of formal specification methods has typically implied extensive initial investment, relatively fixed requirements on top of which a formalization can be established, and relatively slow feedback due to the effort needed for formal modeling. In this paper, we challenge this view of formal methods, and describe how the agile software development approach can be applied with formal methods. We back the discussion on formal method DisCo, which has been intended as a formalization tool for a programmer rather than for a mathematician. Towards the end of the paper, we also give a small example where agility is demonstrated.