Try it like this: go for a walk in nature and focus on the senses. Try to really feel yourself walking, feel the clothes on your body, the wind, the distant sounds. As things enter your perception, be grateful for them. The dogs and children, the leaves and sun. Perhaps contemplate how: (1) this sensation (of ex "dog") feels inside you (2) the miracle of its construction, the billions of particles, the quantum effects underneath, and the orchestral perfection of its movement (3) all the relationships people have with their dogs (4) how dogs affect the entire world

This technique gives you a large "surface area" for gratitude droplets to coalesce. With a little repetition, you can get very high doing this technique, making it fun and self reinforcing. Ultimately all sensations can be integrated into your larger self-experience, changing the small, separate identity, into a large all encompassing compassionate one

My understanding: the fundamental skills are attention (focus/zoning in), awareness (broad attention of sensation), and gratitude (compassion/metta/love). You can train these skills whenever is the most enjoyable, including painting, dance, gardening, working out. Gratitude is the one that makes the most happiness up front, check out the "hedonic treadmill"