Faith Brings Knowledge

'Shraddhavan labhate jnanam matparassamyat indriyaha', (one with faith gains knowledge).
When one has faith, knowledge flows to them. Faith brings the knowledge.
Nobody needed to tell Eklavya to surrender, or to have faith, but Arjuna had to be told. Sri Krishna tells him, 'You better listen to me'.
Krishna had to tell Arjuna, but he did not have to tell Radha, or Yashoda, or Vidhur. But he had to tell Arjuna to surrender and have faith.

First he says, 'Isvarah sarva-bhutanam hrd-dese'rjuna tishthati', God is in everybody’s heart, he is in your heart, take refuge in him.
The he finally says, 'Mam ekam saranam vraja', (you surrender to me).

Later on he tells him of the three persons, 'He' 'You' and 'I' (first person, second persons and third person). So in all the three persons, Sri Krishna has taught Arjuna.

It is so beautiful. If you sit and analyze, so much wisdom comes at every point, that it is amazing.
But he had to tell him, 'Arjun, you better surrender to me', because his mind was here and there. He didn’t have to tell others.
That is the difference. Nobody had to tell Eklavya, his faith was so strong.

There are several reasons to it.
When your bowel movements are not good, if you are constipated, there you get too many negative thoughts. So purification of the body is a must.
When your digestion is good, then mind is clear too.
Second, you should do Pranayams. With Pranayama negative thoughts go away too. Third is, when you keep sitting all day doing nothing and there is not enough blood circulation is in the body, then also you get negative thoughts. To remove negative thoughts, do some exercises, or go for swimming, or for a long walk.
Exercise has a very good effect on the body and the mind. It improves blood circulation and negative thoughts go away from mind.
When the life force energy is low, do Pranayams and meditation. Satsang, good company, light food, all these affect our thoughts.
After doing all these, if negative thoughts still come, then just be a witness to these thoughts.

Both. It is there, but it needs to be increased. Just like how rice is inside the paddy, but the husk on it has to be removed.

There no one solution for this.
When you know that a person is very doubting by nature, then you will not trust everything he says.
Doubt is also important in life, but only as much as salt in food. When it becomes too much, then it is a disease, it is called paranoia.
When it just the right amount, a person stays alert and aware, and does not get into wrong company.
So, just like salt in food, you cannot do away with it completely. But when it is more than required, then Pranayams and meditation helps.