Biggest strugglers and intelligent person
Al-Sheikh Al-Sadooq through his chain of narrators, narrated from Imam Ali (a.s) that the Messenger of God (s.a.w) said:
The biggest strugglers of people who strive are those who avoid sin.
The best of the intelligent people are those who remember death more often.
Source: [Biharul-Anwaar, vol. 77, p.113]
Other links:
Affliction
The characteristics of Real Follower of Ahlul-Bayt
Beauty of soul