Surya who signifies Soul and confidence, Moon who signifies mind or the collection of experiences, and lagna, the relative point of Sun in the horizon at the time considered, which signifies body.
From a proper analysis of these 3 points we can gauge the general strength of a horoscope.
Even if all the other planets are in difficult positions, if these 3 pillars are in strength, the native can be considered solid.
When ascending sign and its lord are weak, it results in a weak constitution.
When Sun occupies 3, 6, 10 and 11, in friendly / strong rasis or signs, the person has optimum level of confidence. Whereas when he occupies 8 and 12 or unfriendly/weak signs, the native will lack in confidence which will ultimately result in either superiority or inferiority complex.
Likewise, when moon occupies difficult houses or signs, the way the native collects experiences will result in negativity.
It is true that a weak Sani/saturn will result in lack of discipline
or Mars will result in lack of vigour/drive..
But with a healthy constitution, confidence and strong mind, you tend to be more successful.