>>1263595In French legion there is an opinion that most important is endurance.
So take a 10 kg bag and go for a trip, gradually increase weight of the bag to 30 kgs and also increase your speed.
But also consider whether it wouldn't be best to just avoid being drafted, for that it might be the best to be in the worst physical condition imaginable. Maybe also pretend to have mental health issues. Or just leave country, if you are Russian I don't think it should be too hard to get asylum as conscientious objector.