Emerald

My advice is to make it a part of your daily routine, just like brushing your teeth. Start with 10-20 minutes at first, and once you've made a habit out of that you can add more minutes to your daily practice as you progress. Don't go into it with the mindset the you have to sit for at least an hour. Unless you're like Leo, this will likely be a recipe for failure because it's too big of a commitment too soon.

The ego will manufacture obstacles to keep you from enlightenment. It doesn't want to have its importance undercut. Your exhaustion is likely a very sneaky thing your ego is doing to derail your progress. Be mindful of the exhaustion itself and you may become conscious that it isn't real bodily fatigue but psychologically created emotional fatigue sent from the ego to act as a protection mechanism. My advice is to push through the difficult emotions, and continue on the path.

Being a sentient being (or a living organism in general) entails self-interest. There is no way to escape self-interest in a genuine way, even from an enlightened perspective. However, the enlightened have dis-identified with the separate self and thus realize that the self encompasses everything in existence. So, from an enlightened perspective, helping others IS self interest. However, make no mistake that any attempt to be helpful is influenced by self-interest. But it is just as self-interested NOT to do it, so go ahead and help... but be mindful. Notice how your desire for selflessness is self interested.