John Piper defines love as “the overflow of joy in God that gladly meets the needs of others” (Desiring God, p. 119).
Love, or serving others, does involve joy—it is pleasing to ourselves. Paul told the Thessalonians, “You are our glory and joy” (1 Thessalonians 2:20). The Macedonian churches loved out of joy (2 Corinthians 8:1–4). Joy is there.
In terms of Romans 15:1–2, the “not pleasing ourselves” means that we shouldn’t set our private comforts as a greater joy than seeing the joy of our neighbors.
Piper writes,
“[Paul] does not mean we shouldn’t seek the joy of edifying others, but that we should let this joy free us from bondage to private pleasures that make us indifferent to the good of others. Love does not seek its own private, limited joy, but instead seeks its own joy in the good — the salvation and edification — of others. In this way, we begin to love the way God loves. He loves because he delights to love.” (p. 116).