Despairing About Meditative Regularity I have set the amount of time I meditate (focused attention/shamatha) at merely 15 minutes per day. Despite this, despite all my best efforts, I seem to still skip a day or two now and then. 

Why is this? Would changing the type of meditation help?

I had read positive emotions help develop a habit. When I meditate mindfully on the breath, there are no such emotions; doing compassion meditation, positive affect arises. Would this affective benefit motivate a meditative practice?
Having spend a mindful day with dana, a day having begone with refuge, spend with Sila, one is able to rejoice:

Buddhanussati, 2 min remembering the Buddha
Dhammanussati, 2 min remembering the Dhamma
Sanghanusati...

Remember ones Generosity
Remember ones Virtue
Remember/reflect ones virturs equal the Devas

Having given causes, one gains concentration. Not having given causes, trying to concentrate by effort will always be just developing wrong concentration.

Useless to invest in a roof when foundation is not given.

Duties first: this is not a path for lazyness's fruits. Not the path of demanding and claims.