What's actually happening
Mars takes roughly two years to complete one circuit of the zodiac, spending an average of six to seven weeks in each sign during direct motion. Sagittarius is a mutable fire sign ruled by Jupiter.
What the tradition makes of it
Mars in Sagittarius is the drive oriented toward expansion rather than acquisition. The action here is motivated by belief — by the conviction that what is being pursued matters beyond the immediate practical result. The effort is generous and sometimes reckless; the Sagittarius influence pushes past ordinary caution in service of a larger vision.
The tradition describes this placement as well suited to crusades in the best sense: the directed effort toward something worth fighting for, the willingness to go further than circumstances make strictly necessary because the cause demands it.
The shadow is grandiosity and dispersal. Sagittarius at its most inflated believes it is pursuing the most important thing in the world; at its most scattered, it abandons each pursuit as soon as the next important thing appears on the horizon.
How to actually use it
Act from conviction. This is good weather for the effort that carries genuine meaning — for the project that is larger than self-interest, for the work that requires both energy and belief to sustain. Let the cause be real before the pursuit begins.
The practice is to stay with one thing long enough to know whether the belief survives contact with the actual work of it.
When in doubt
What do you believe enough to keep moving toward, even when it is difficult?