- Mars in Gemini opposes Saturn Rx in Sagittarius: 25 degrees
The pressure to act or choose increases because of restrictions. You're blocked or denied by external rules, or someone's authority. And yet, there's something you have to do. There's a responsibility - work to be done. As a culmination aspect, it can deliver endings, results of previous work, or results of what hasn't been done.
The harder you push, the more resistance there is. Brute force and temper tantrums won't work. You may be so angry, but are not allowed to express it. What to do? Suss out the path you need to take, and the choice you need to make. There can only be one (Saturn narrows your options, especially when he's Rx). Do what you have to do. Be calm, be persistent.
Another possibility is swinging between full stop (Saturn) and scattered efforts (Mars in Gemini). Hopping wildly from here to there, then running into a wall and giving up. The best way to deal with any opposition is to find that balance point. Aim for a slow, steady release of energy. Focus, then take it one step at a time.
This opposition is the backbone of the Kite I discussed here. That's a good thing, because nothing says "backbone" like Saturn. This is one of the strongest aspects in existence. You know what you're up against - act accordingly. Your mature (Saturn) actions (Mars) are the release point of that Kite.