Ground flaxseeds are a great source of omega 3. Two tablespoons of ground flaxseeds provide you with enough ALA, EPA, and DHA.
If you don't want to grind flaxseeds, you can just take two tablespoons of chia seeds per day. Chia seeds have approximately the same amount of ALA as flaxseeds but you don't need to grind them. You can just mix them in with your smoothie. If you're really lazy like me, just buy microalgae-based DHA supplements.