Seva should walk hand in hand with sadhana(spiritual practices). If one is absent, you will not gain anything from the other.
From sadhana you get strength to do seva, and from seva you get depth in sadhana.
But remember that sadhana is your first priority! You should make time to do sadhana, you should be smart in managing time.
There is no end to work, there is always work every day. So make time for sadhana.
- Gurudev Sri Sri ..