Mars opposing its own natal position puts your current assertive energy in direct confrontation with the way you habitually express drive. This one is often felt through other people's aggression or competitiveness.
A Mars opposition to natal Mars is a halfway point in the two-year Mars cycle. What you initiated at the Mars Return is now being tested by external circumstances. Someone pushes back. Competition shows up. The way you have been using your energy gets challenged by reality.
This is not a pleasant transit but it is a useful one. The opposition reveals whether your current approach to assertion is working. If it is then the friction is manageable and the outcome is progress. If it is not then the confrontation exposes the flaw.
What you might notice: Direct confrontations or competitive encounters. Other people embodying the drive you are not expressing. A test of your current approach to conflict. Physical tension that demands release.
Astro Transit Academy is an educational resource for exploring transit astrology. The information here is not personal advice or prediction. Astrology is a framework for self-reflection, not a script for living.