Mental Attribute Training

Overview
The mental attributes Composure and Leadership can be improved, though not strictly by training them, but rather by having players play in competitive matches. It works as follows:

Composure
Every 15 seconds (15 seconds is equivalent of 2.5 minutes in an 80 minute match) playing time in a competitive match (league and cup matches) a player gains 0.4% CPL added to their Composure.

Leadership
Players automatically gain Leadership when they are picked as captain. Players not chosen as captain have a chance of gaining an increase to leadership based upon the position they play during a competitive match:

Any player that is picked as your captain in a competitive match (league and cup matches) will gain 0.4% CPL level per 15 seconds played (15 seconds is equivalent of 2.5 minutes in an 80 minute match).

Any non-captain that gains a leadership boost from a competitive match (league and cup matches) will gain 0.2% CPL level per 15 seconds played (15 seconds is equivalent of 2.5 minutes in an 80 minute match).

CPL% Explained
To work out what 100% of CPL would provide, look at the raw skill points it would take to for a skill to rise from the level below the CPL to the CPL level (see Skill Training Gains for more details on skill points)

Example
A beginning club has a CL (club level) of 1. A CL of 1 means the club has a CPL of 15. To work out how many raw skill points 100% of 15 CPL provides you look to see how many raw skill points is required to gain a skill level of 15 from level 14, which is 200 raw skill points (level 15 is 2030 points and level 14 is 1830, so the difference is 200 points). So 100% of CPL 15 would add 200 raw skill points to something being trained at 100%CPL. To continue the example, a player picked as captain in this team would gain 0.8 points (0.4% CPL%) per 15 seconds played.