Static Apnea training and a new PB

I've enrolled for a freediving course, so I'm trying some of the training exercises from the manual before the course starts. In doing so, I managed to increase my static Apnea PB to 3:54 min (previous was 3:36). The process of building up to it gradually, meant it was a much more enjoyable experience and a good half hour meditation.

CO2 static apnea (dry)

Increase high CO2 tolerance

Split	Phase	Time
1	Breath-up	2:00
2	Breath hold	1:00
3	Breath-up	1:45
4	Breath hold	1:00
5	Breath-up	1:30
6	Breath hold	1:00
7	Breath-up	1:15
8	Breath hold	2:00
9	Breath-up	1:00
10	Breath hold	2:00
11	Breath-up	0:45
12	Breath hold	2:00
13	Recover	0:30
10	Breath hold	2:00
11	Breath-up	0:15
12	Breath hold	2:00

O2 static apnea (dry)

Increase low O2 tolerance.

Split	Phase	Time	Avg HR
1	Breath-up	02:05.3	75
2	Breath hold	01:45.6	82
3	Breath-up	02:02.0	75
4	Breath hold	02:08.2	74
5	Breath-up	02:02.4	74
6	Breath hold	02:17.8	74
7	Breath-up	02:05.7	77
8	Breath hold	02:47.0	76
9	Breath-up	02:07.9	75
10	Breath hold	02:48.2	75
11	Breath-up	02:02.4	79
12	Breath hold	03:53.9	73
13	Recover	02:53.6	75
Summary		31:00.0	75