Reactivity-Proactivity:

Reactive actions form a response from internal capability to some current or past external context. Proactive actions form a response from internal capability to some anticipated future external context. (By comparison, a passive state is product of internal capability without any consideration of external context - it's just something you're doing anyway.)

Generally, it's better to be proactive when you can: making concerted efforts to understand, adapt and influence your context so that you can achieve your goals.

However, there will be situations in which outside context problems will occur, too. The universe is a chaotic place, and if your challenges are complex then you will inevitably have to react to something unanticipated. (This is especially true when you have low influence relative to other entities or forces that can help or harm your chances of achieving your goals.)

This is where initiative comes in. If you want to get something achieved, then you need to be able to take the initiative to get it done. Strong proactive capacity can help you to perceive and anticipate risks, plan contingencies for them, and build initiative. Strong reactive capacity can help you to re-evaluate your position and quickly create new plans to maintain or regain initiative.