A few words on Karmas
Karmas (not the upanishadik karma which the textbook philosophers developed into the theory of Karma) are essentially four-fold.
1.. Nityakarmaas... Sandhyavandhanam, Samidhaadhaanam, Aupasanam, Brahmayagnam, etc.,
2.. Naimithika karmas... consequential duties...taking bath when one is polluted, special karmas when guests come, when a particular incident happens like birth or death, performances of some particular dates of special vedic rites, pithrukaaryams etc.
3. Kaamya karma.. Rituals with some particular aim or expectation, yaagaas like ashwamedha, rajasooya, atiratra, vaajapeya etc. Navagraha yashti, Sudharsana Homa, Mrityunjaya, Aaayushy Homas, Tila Homas, the list is huge.
4. Nishkaama Karma.. Prayer to god without any personal agenda, study of purnas and itihasas, discourse of the messages without expectation for any returns, service of the weak, gifts without any desire for punya etc... philanthropy if this is to be explained though a single word.
Soundaka and Yajnavalkya have prescribed that if there is a break in performance of Sandhyavandhanam for seven days, the eligibility for doing the karma is lost and the person has to be initiated to nityakarma and gayatri afresh. The subject of aachamanam will be dealth with shortly.