Hatha yoga cannot succeed without Raja yoga, nor Raja without hatha.
Therefore, practice the two to perfection 
(Hatha Yoga Pradipika, 2-76)

Finding and maintaining the balance between physical and meditative practices can be challenging at time for anyone on a journey of self development.
I realised early on in my yoga journey that Hatha yoga wouldn’t be enough.
Sure, Hatha yoga practices make the body strong and flexible. And yes, freeing the body and breath from limiting patterns increases energy and will power, opening new possibilities. Through hatha yoga practice, we become emotionally freer, stronger and more resilient.
The Buddha himself advised that “If the body isn’t cultivated, the mind cannot be cultivated. If the body is cultivated, then the mind can be cultivated.” The practice of asana and pranayama is an excellent way to build mindfulness of the body, the first foundation of mindfulness. But if we neglect to develop the healthy qualities of heart and mind that support this mindfulness, its gifts are mostly aimless. And to develop these qualities, we need the container of ethical practices.

Raja Yoga Swami Purohit, in his commentary on the Yoga sutra (ISDN 0571103200), wrote: “I met many who practiced Hatha yoga as a stepping stone to Raja yoga, but the few who were mere Hatha yogis had great powers, strong healthy bodies and immense vanity. (…) They were generally amenable to praise, and some more worldly than average worldly men. This was the chief reason why I lost faith in Hatha yoga.
And indeed, time and time again over the past 25 years, I have met great hatha yoga practitioners who, without the preliminary ethical practices of yama and niyama fell victim to pride, greed or lust. Their mind lacked stability, and their lives often reflected this.

Buddhist teachers seem to fare much better in that department. Their rigorous training in ethical and meditative practices apparently produced a far more stable mind. Although some of them sometimes fall victim to greed and delusion as well, their training in mindfulness, or simply peer pressure, meant this is less obvious and less frequent.
But, I also frequently met on meditation retreats long term Buddhist practitioners who didn’t seem to make much progress. Their sitting posture was poor, and they didn’t seem to have much awareness of it. They had been struggling with the same hindrances for years, and while they had often developed a high degree of tolerance for discomfort and could sit them out, progress was slow at best. They clearly would have benefited from some hatha yoga practices.

In my own practice, I have found that keeping a balance between the ethical and meditative practices of Raja yoga and the physical practices of Hatha yoga is indeed the best way to ensure steady progress.
Swatmarama knew what he was talking about:)

Christophe Mouze
I'm one of the founders of Sati yoga and the webmaster of this site.