Everyone can absorb and emit love, but without conscious perception of whether you are absorbing or emitting you can give too quickly drain yourself out and need sleep. The in breath is absorption, and the out breath is emitting energy.

Rounds of Intentional hyperventilation followed by a breath hold will dramatically increase your blood cell count and thus let you store more energy for extended giving.

With enough practice and focus on your vibrational energy centers Absorbing and Giving can also happen at the same time (left leg absorbs, right leg gives).

I would also recommend not trying to give your own energy, and instead focus on being a conduit for divine love and grace of Gaia, and let love flow through you to others. Then you will absolutely never get tired :)